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Understanding engineering geology

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Understanding Engineering Geology is a brief description of Engineering Geology aimed at helping students undertaking Bachelor of Civil Engineering get an idea about the course.

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Understanding engineering geology

  1. 1. Luwalaga John Groover MSc.PH (IHSU); B.Eng. Civil (KYU); H.Dip. Civil (KYU); Dip. Arch. (UPK) 2010 Edition
  2. 2. 2 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) KYAMBOGO UNIVERSITY FACULITY OF ENGINEERING DEPARTMENT OF CIVIL AND BUILDING ENGINEERING CE 225: ENGINEERING GEOLOGY FOR B.ENG. CBE II AND BEEEM II FEBRUARY 2011
  3. 3. 3 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) Table of Contents CHAPTER ONE ...................................................................................................................................9 1.0 INTRODUCTION...............................................................................................................9 1.1 Brief Description of the course ................................................................................9 1.2 Objective of the course ................................................................................................9 1.3 Geology ...............................................................................................................................10 1.4 Work of Geologist.......................................................................................................10 1.5 The Scope of Geology ..............................................................................................10 1.5.1 Physical geology........................................................................................................10 1.5.2 Historical Geology ....................................................................................................11 1.6 Civil Engineering.........................................................................................................12 1.7 Engineering Geology.................................................................................................12 1.8 Why study Geology ....................................................................................................12 1.9 Activities of Engineering Geologists in Civil & Building Engineering Industry............................................................................................................................13 CHAPTER TWO.................................................................................................................................14 2.0 THE PLANET EARTH AND ITS SURROUNDING..............................................14 2.1 Universe...........................................................................................................................14 2.2 The Solar System........................................................................................................14 2.3 The Planet Earth .........................................................................................................19 2.4 The Age of the Earth................................................................................................20 2.5 The Internal Structure of the Earth ..................................................................20 2.5.1 Crust.................................................................................................................................22 2.5.2 Mantle..............................................................................................................................22 2.5.3 Core ..................................................................................................................................22 2.6 The Theory of Plate Tectonics...........................................................................23
  4. 4. 4 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) 2.7 Continental Drift ........................................................................................................23 2.7.1 Evidence Supporting Continental Drift ..........................................................24 2.8 Sea-Floor Spreading.................................................................................................25 Formation of an Oceanic Ridge .............................................................................................25 2.9 Geological Time Scale...........................................................................................................26 CHAPTER THREE............................................................................................................................28 3.0 MINERALOGY..................................................................................................................28 3.1 INTRODUCTION...........................................................................................................28 3.2 SUMMARISED UGANDA MINERAL INVENTORY AND THEIR USES ..29 3.3 Identification of Minerals and their Properties ..........................................36 3.3.1 Physical Properties of Minerals..........................................................................36 3.3.2 Microscopic Optical Properties of Minerals.........................................42 3.3.3 Chemical Properties of Minerals........................................................................44 CHAPTER FOUR ..............................................................................................................................50 4.0 PETROLOGY......................................................................................................................50 4.1 Definitions ......................................................................................................................50 4.2 Rock Cycle .....................................................................................................................50 4.3 Types of Rocks ............................................................................................................52 4.3.1 Igneous Rocks (Eruptive Rocks).......................................................................52 4.3.2 Sedimentary Rocks/Stratified/Secondary Rocks ....................................56 4.3.3 Metamorphic Rocks ..................................................................................................60 CHAPTER FIVE.................................................................................................................................63 5.0 STRUCTURAL GEOLOGY............................................................................................63 5.1 Definitions ......................................................................................................................63 5.2 Folds ..................................................................................................................................64 5.2.1 Causes of Folding......................................................................................................64 5.2.2 Parts of a fold and connected terminology .................................................65
  5. 5. 5 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) 5.2.3 Types of Folds.............................................................................................................68 5.2.4 Engineering Considerations involved in Dealing with Folded Rocks............................................................................................................................................70 5.3 Fractures in Rock......................................................................................................71 5.3.1 Joints ................................................................................................................................72 5.3.2 Faults...............................................................................................................................73 CHAPTER SIX ...................................................................................................................................77 6.0 EARTH QUAKE.................................................................................................................77 6.1 Definition.........................................................................................................................78 6.2 Causes of Earthquakes and their types .........................................................78 6.3 Seismic waves .............................................................................................................79 6.4 Types of seismic waves.................................................................................80 6.4.1 Body waves: ..................................................................................................................80 6.4.2 Surface waves..............................................................................................................80 6.5 Measuring of the size of an Earthquake.........................................................81 6.5.1 Intensity: .........................................................................................................................81 6.5.2 Magnitude:......................................................................................................................81 6.6 Effects of earthquakes ............................................................................................83 6.7 Tsunami:..........................................................................................................................85 CHAPTER SEVEN............................................................................................................................86 7.0 GEOTECHNICAL METHODS OF SITE INVESTIGATION ..............................86 7.1 Definitions ......................................................................................................................86 7.2 Objectives.......................................................................................................................86 7.3 Steps involved in Site Investigation.................................................................87 7.3.1 Desk study......................................................................................................................87 7.3.2 Site reconnaissance.................................................................................................88 7.3.3 Ground investigation ................................................................................................88
  6. 6. 6 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) CHAPTER EIGHT.............................................................................................................................91 8.0. TUNNELING..............................................................................................................................91 8.1 Definitions......................................................................................................................91 8.2 Merits and demerits of tunnels..........................................................................91 8.3 Tunnel approaches ....................................................................................................92 8.4 Shape and size of tunnel cross-sections.......................................................93 8.4.1 Shapes of tunnel cross-section .........................................................................93 8.4.2 Size of Tunnel cross-section. .....................................................................96 8.5. Types of tunnels................................................................................................................96 a) Traffic tunnels....................................................................................................................96 b) The Hydro power tunnels.............................................................................................97 c) The Public Utility Tunnels............................................................................................98 8.6 Geological considerations required for successful tunneling operations in consolidated and unconsolidated rocks..........................98 8.6.1 Tunneling in consolidated rocks.......................................................................98 8.6.2 Tunneling in unconsolidated rocks .................................................................99 CHAPTER NINE..............................................................................................................................100 9.0. PROCESS OF WEATHERING AND DENUDATION ................................................100 9.1 Introduction: General, sources and definitions........................................100 9.2 Types of weathering...............................................................................................101 9.2.1 Mechanical weathering or disintegration ...................................................101 9.2.2 Chemical weathering. ............................................................................................103 9.2.3 Biological Weathering............................................................................................107 9.3 Agents of erosion......................................................................................................108 9.3.1 Water...............................................................................................................................108 9.3.2 Wind.................................................................................................................................108 9.3.3 Erosion by moving ice. ..........................................................................................108
  7. 7. 7 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) 9.4 Factors affecting rate of Weathering.............................................................109 9.5 Importance of weathering ...................................................................................110 9.6 Short coming of weathering ...............................................................................110 CHAPTER TEN................................................................................................................................111 10.0 GEOLOGICAL ASPECTS OF BUILDING STONES AND AGGREGATES. ...............................................................................................................................111 10.1 Introduction................................................................................................................112 10.1.1 Rock ........................................................................................................................112 10.1.2 Stone.......................................................................................................................112 10.2 Uses of stones ..........................................................................................................112 10.3 Seasoning of stone.................................................................................................113 10.4 Characteristics of stones ...................................................................................113 10.5 Decay or degradation of Stones......................................................................114 10.6 Preservation of stones .........................................................................................115 10.6.1 Examples of preservatives................................................................................115 10.7 Quarry and Quarrying............................................................................................116 10.8 Selection of Quarry site.......................................................................................116 10.9 Different methods used in stone Quarrying ..............................................116 CHAPTER ELEVEN.......................................................................................................................118 11.0 GEO-HYDROLOGY.......................................................................................................118 11.1 Origin of ground water...........................................................................................118 11.2 Definition......................................................................................................................119 11.3 The hydrologic cycle.............................................................................................119 11.4 Occurrence of Groundwater..............................................................................120 Porosity......................................................................................................................................121 Permeability............................................................................................................................122 Water table ..............................................................................................................................124
  8. 8. 8 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) Perched water table ...........................................................................................................124 Drainage of Ground water ...............................................................................................124 Specific yield..........................................................................................................................124 Specific retention or field capacity............................................................................125 11.5 Wells................................................................................................................................125 11.5.1 Types of wells....................................................................................................125 11.6 Aquifers. ........................................................................................................................127 11.6.1 Types of Aquifers .............................................................................................128 11.7.1 Formation and types of springs................................................................131 11.8 Isotropy and Anisotropy........................................................................................132 11.8.1 Isotropy (KV = KL)................................................................................................132 11.8.2 Anisotropy (KL >>>>> KV).....................................................................................132 11.9 Potentiality of different Rocks as Aquifers ...............................................132 11.9.1 Sedimentary rocks as aquifers.................................................................132 11.9.2 Metamorphic Rocks as Aquifers..............................................................133 11.9.3 Igneous Rocks as Aquifers..........................................................................133 11.10 Groundwater Prospecting....................................................................................133 11.10.1 Objectives of hydro-geological investigation................................134 11.10.2 Methods of exploration .............................................................................134 11.10.3 Logs or recording of Bore-hole Data..................................................136 BIBLIOGRAPHY .............................................................................................................................149
  9. 9. 9 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) CHAPTER ONE The ancient Romans had a tradition: whenever one of their Engineers constructed an arch, as the capstone was hoisted into place, the Engineer assumed accountability for his work in the most profound way possible: he stood under the arch. Michael Armstrong. U.S. business executive, speech 1.0 INTRODUCTION 1.1 Brief Description of the course  Introduces the fundamental aspects of geological processes and materials.  Examines the close linkage with our everyday life as well as with civil and water engineering constructions of common good. 1.2 Objective of the course By the end of this course (Engineering Geology) students should be able to:  Describe and identify the different types of rocks in order of formation and their physical properties;  Observe and record geological information and then translate this data to practical engineering design, construction and maintenance of civil engineering projects;  Explain the rocks’ contributions to groundwater quality purification and deterioration;  Identify the chemical, mineralogical composition and structures of these rocks and their effects to construction structures;  Identify groundwater flow pattern within the different types of rocks in the world;  Describe fully and identify the biological properties the rocks offer to weathering processes.  Definition of Geology  Work of Geologist  The Scope of Geology  Definition of Civil Engineering  Definition of Engineering Geology  Why study Geology SUMMARY
  10. 10. 10 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) 1.3 Geology The term Geology comes from the Greek words Geo + Logos. Geo means Earth, and Logos means study or science. Geology therefore, deals with the study of the planet Earth on which we are living. The science of Geology tells us about the origin, structure and history of the Earth and its inhabitants, as recorded in the rocks. Without its study, one remains ignorant about the same planet on which we are living. Geology is a branch of natural science devoted to the study of the physical features of the earth, the composition and structure of the rocks composing it, the forces at work in altering it, and the record of the animals and plants that have lived on its lands and inhabited its seas. 1.4 Work of Geologist Geologists seek to understand how the earth formed and evolved into what it is today, as well as what made the earth capable of supporting life. A geologist is concerned with every aspect of the composition and structure of the earth’s crust. His/her sphere of work is therefore world-wide; his/her main laboratory is the great out-of-doors where he/she examines rocks as they actually occur in nature. His/her considerations range from the beginning of time and into the future, even to that time when man will no longer be on earth. He/she studies all that composes the crust of the earth sphere and especially those materials of use to his/her fellow man. 1.5 The Scope of Geology The scope of geology is so broad that it has been split into two (2) major divisions:- 1. Physical geology 2. Historical geology 1.5.1 Physical geology It deals with the Earth’s composition, structure, the movements within and upon the Earth’s crust, and the geologic processes by which the Earth’s surface is, or has been changed. This division of geology includes in itself, the following branches:- Mineralogy: - This deals with the study of minerals. Minerals are basic constituents of rocks, and thus, influence the properties of the rocks. Hence in order to know the properties of the rocks, one has to study the properties of the minerals.
  11. 11. 11 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) Petrology: - The term Petrology is derived from the Greek word, Petro + Logos. Petro means rocks and Logos means study. Hence Petrology means the study of the rocks. Since the Earth’s crust, also called lithosphere (solid outer layer of the Earth above the asthenosphere, consisting of the crust and upper mantle), is composed of different types of rocks, their study is done under this branch, which deals with the study of mode of formation, structure, texture, composition, occurrence, types, etc. of the various rocks of the Earth’s crust. Structural Geology: - The rocks which constitutes the Earth’s crust, have undergone and continues to undergo various deformations, dislocations under the influence of tectonic forces; causing formation of geological structures like folds, faults, joints, etc., in the rock masses. The details of their mode of formation, causes, types, classification, importance, etc, are studied in this branch of physical geology. Geomorphology: - This branch of geology explains and studies the origin of various surface features of the Earth. Economical Geology: - This is a specialized division of mineralogy and petrology, wherein the products of the Earth’s crust having good economic value, are studied. Valuable ores containing metals, like coals, petroleum, etc, do come under the domain of this specialized study. It includes the study of their occurrence, search, and exploitation for commercial and industrial uses. 1.5.2 Historical Geology This deals with the study of the origin and evolution of the Earth and its inhabitants. The various sub-divisions of this branch of geology includes:- Stratigraphy: - The term stratigraphy comes from the Greek words: Strata + Graphy. Strata mean the sets or beds of sedimentary rocks; while Graphy means the description. Stratigraphy deals with the study of the beds of the sedimentary rocks. The study thus helps in identifying the ages of the rocks of the various regions and areas, thereby assisting in describing in detail their general civil engineering uses. The study of these rocks involves extraction of fossils, i.e. the remains of plants and animals of the past geological Eras. Palalentology: - Deals with the study of the ancient organisms, plants, and animals, etc; as revealed from their remains and remnants (i.e. fossils), the study helps in
  12. 12. 12 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) providing a background to the development of life on Earth, over the past geological Eras. Palaeogeography: - This branch of science deals with the study of the geographic conditions of the past times. It, thus deals with the reconstruction of the relations of the ancient lands and seas, and the organisms that inhabited them. 1.6 Civil Engineering Civil Engineering is defined as the art that includes the design and construction of all structures other than simple buildings, and the investigation, design, and construction of all systems of transportation, natural power development, water supply and sewage disposal, as well as the direction of natural forces for the use and convenience of man. Every branch of civil engineering has some contact with the surface of the earth. For instance, the works designed by the civil engineer being supported by or located in some part of the earth’s crust. The practice of civil engineering includes the design of these works and the control and direction of their construction. 1.7 Engineering Geology Engineering geology is the application of engineering principles to geologic problems. Two fields of Engineering that use geology extensively are civil Engineering and Mining geology Engineering. For example, the stability of a building or bridge requires an understanding of both the foundation material (rocks or soil) and the potential for earthquakes in the area. 1.8 Why study Geology  To classify and know the types of rocks  To differentiate the types of minerals and their properties  To appreciate geological structures such as faults, folds, joints, bedding, etc  To determine the strength and behavior of geological materials  To be able to understand and carryout ground investigations  To understand the earth’s endogeonetic and exogeonetic processes e.g. weathering, erosion, failure of slopes, etc  To be able to interpret Geological Maps  To understand characteristic of ground water bodies
  13. 13. 13 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com)  To facilitate excavations in rocks and soils during mining, tunneling, etc  To be able to determine foundations and embankments for reservoirs, dams, etc  To help identify suitable locations for landfills 1.9 Activities of Engineering Geologists in Civil & Building Engineering Industry Investigation of foundations for all types of major structures, such as dams, bridges, power plants, airports, large buildings and towers; Evaluation of geological ground conditions along tunnels, mines, pipelines, canals, railway, and highway routes; Exploration and development of sources of rock, soil and sediment for use as construction material; Investigation and development of surface and groundwater resources; groundwater basin management; protection and remediation of groundwater resources; Evaluation of geological hazards such as landslides, faults and earthquakes, seismic hazards, radon, asbestos, subsidence, expansive and collapsible soils, expansive bedrock; The evaluation of geological conditions affecting residential, commercial, and industrial land use and development; Foundation investigation, slope stability and excavatability; The safe disposal of waste to the Earth; In cooperation with the civil engineers, Engineering geologists have a big role in ensuring public safety, health and welfare in relation to engineering works. In some countries like the US, the profession laws require participation of engineering geologists in approving construction plans. Geology is pro-people. It exists because people want to modify the geological environment for their use and convenience; they want to work and live safely in harmony with the environment. Geologists can determine which geological environment is good and safe for construction.
  14. 14. 14 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) CHAPTER TWO John 1:1-4 In the beginning the Word (Jesus Christ) already existed. The Word was with God, and the Word was God. He existed in the beginning with God. God created everything through Him and nothing was created except through Him. The Word gave life to everything that was created, and His life brought light to everyone. 2.0 THE PLANET EARTH AND ITS SURROUNDING 2.1 Universe The Universe is the totality of all matter and energy that exists in the vastness of space, whether known to human beings or not. 2.2 The Solar System The solar system (sun and bodies orbiting it) is the sun and all the planets, asteroids, meteors, and comets that are subject to its gravitational pull.  The Solar System  The Planet Earth  The Age of the Earth  The Internal Structure of the Earth  The Theory of Plate Tectonics  Continental Drift  Sea – floor spreading  Geological Time Scale SUMMARY
  15. 15. 15 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) The Solar System consists of nine major planets (including the earth) moving around a central body – SUN. These planets includes:- Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto. The nine major planets and their moons (32) are revolving in nearly the same plane around the sun. In addition to this movement around the sun, these planets are undergoing constant rotation about their own axis. Among the nine planets, only the earth is the only planet which is certainly known to support life. 2.2.1 Important Facts about the Solar System No. Name of the Planet Average distance from the sun (million Km) Equatorial Diameter (Km) No. of Moon Length of time for 1 trip around the sun Length of time for 1 revolution about the own axis 1 Mercury 57.91 4878 0 88 days 59 days 2 Venus 108.2 12100 0 224 days 243 days 3 Earth 149.6 12756- 12714 1 365 ¼ days 23hrs, 56min, 1sec. 4 Mars 227.94 6793-6753 2 1.9 years 24hrs, 37min 5 Jupiter 778.33 142880- 133540 12 11.9 years 9hrs, 50min 6 Saturn 1426.98 120000- 106900 10 29.5 years 10hrs, 14min
  16. 16. 16 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) 7 Uranus 2871 50800- 49400 5 84 years 10hrs, 49min 8 Neptune 4497 48600- 47500 2 164.9 years 15hrs, 48min 9 Pluto 5914 5500 0 248 years 6.4 days Mercury orbits closer to the Sun than any other planet, making it dry, hot, and virtually airless. Although the planet’s cratered surface resembles that of the Moon, it is believed that the interior is actually similar to Earth’s, consisting primarily of iron and other heavy elements. This composite photograph was taken in 1974 by Mariner 10, the first probe to study Mercury in detail. Venus is the brightest object in our sky, after the sun and moon. Swirling clouds of sulfur and sulfuric acid obscure Venus’s surface and inhibited study of the planet from Earth until technology permitted space vehicles, outfitted with probes, to visit it. These probes determined that Venus is the hottest of the planets, with a surface temperature of about 460° C (about 860° F). Scientists believe that a greenhouse effect causes the extreme temperature, hypothesizing that the planet’s thick clouds and dense atmosphere trap energy from the sun.
  17. 17. 17 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) Earth. An oxygen-rich and protective atmosphere, moderate temperatures, abundant water, and a varied chemical composition enable Earth to support life, the only planet known to harbor life. The planet is composed of rock and metal, which are present in molten form beneath its surface. Mars. The most detailed information available about Mars has come from unpiloted spacecraft sent to the planet by the United States. From this data, scientists have determined that the planet’s atmosphere consists primarily of carbon dioxide, with small amounts of nitrogen, oxygen, water vapor, and other gases. Because the atmosphere is extremely thin, daily temperatures can vary as much as 100 Celsius degrees (190 Fahrenheit degrees). In general, surface temperatures are too cold and surface pressures too low for water to exist in a liquid state on Mars. The planet resembles a cold, high-altitude desert. Jupiter is the largest of the planets, with a volume more than 1,300 times greater than that of Earth. Jupiter’s colorful bands are caused by strong atmospheric currents and accentuated by a dense cloud cover. The massive planet, upper right, is shown here with its four largest satellites: Io, upper left, Ganymede, lower left, Europa, center, and Callisto, lower right.
  18. 18. 18 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) Saturn, distinguished by its rings, is the second largest planet in the solar system. This processed Hubble Space Telescope image shows the planet’s cloud bands, storms, and rings as they would appear to the human eye. Uranus. Uranus’s blue-green color comes from the methane gas present in its cold, clear atmosphere. The dark shadings at the right edge of the sphere correspond to the day-night boundary on the planet. Beyond this boundary, Uranus’s northern hemisphere remains in a four-decade-long period of darkness because of the way the planet rotates. Neptune. This image of Neptune, taken by the Voyager 2 spacecraft, shows the planet’s most prominent features. The large, dark oval surrounded by white clouds near the planet’s equator is the Great Dark Spot, a storm similar to Jupiter’s Great Red Spot. The smaller dark oval with a bright core below and to the right of the Great Dark Spot is another storm known as Dark Spot 2.
  19. 19. 19 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) 2.3 The Planet Earth Earth (planet), the third planet in distance from sun in the solar system, the only planet known to harbor life, and the home of human beings Nearly two-thirds or about 71% of earth’s surface is covered by water, which is essential to life. The rest is land, mostly in the form of continents that rise above the oceans. Pluto is farther from the Sun than the major planets in the solar system, although it occasionally moves in closer than Neptune due to an irregular orbit. The small, rocky, and cold world takes 247.7 years to revolve around the Sun. This artist's rendition depicts Pluto, foreground; its moon, Charon, background; and the distant Sun, upper right.
  20. 20. 20 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) Illustration of the earth North Pole Polar (12714 Km) Equator (12756 Km) Circumference (40, 000 Km) South Pole The earth has a Polar diameter of 12714 Km, Equatorial diameter of 12756 Km, Circumference of 40,000 Km; surface area of about 510 x 106 Km2, volume of about 1042 x 109 Km3, mass of about 5.97 x 1021 tones; average distance from the sun is 150 x 106 Km, length of time for one trip around the sun is 365 ¼ days, length of time for one revolution about the own axis of about 24 hours and average temperature of 14oC. In shape, the earth is like an oblate spheroid, i.e. with the exception of a slight flattening at the poles, the earth is nearly spherical or ball shaped. 2.4 The Age of the Earth Geochronologists are responsible for determining the age of the earth using radioactivity technique (radiometric dating technique). This can be achieved by using modern estimates of the age of rocks which form the earth’s crust and are based on determinations on radioactive minerals contained in the rocks. The age of the earth has been estimated to be about 4.55 billion years. 2.5 The Internal Structure of the Earth The known volume and mass of the earth gives its mean density to be 5.5 g/cm3, yet the mean density of rock forming the outer part is 1.126 and 3.1 g/cm3. Thus its greatest mass is concentrated towards the centre. Evidence from seismic waves shows that the earth is layered. The earth basically consists of 3 layers:- 1) Crust 2) Mantle 3) Core
  21. 21. 21 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) The Earth is made up of a series of layers that formed early in the planet’s history, as heavier material gravitated toward the center and lighter material floated to the surface. The dense, solid, inner core of iron is surrounded by a liquid, iron, outer core.
  22. 22. 22 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) The lower mantle consists of molten rock, which is surrounded by partially molten rock in the asthenosphere and solid rock in the upper mantle and crust. Between some of the layers, there are chemical or structural changes that form discontinuities. Lighter elements, such as silicon, aluminum, calcium, potassium, sodium, and oxygen, compose the outer crust. 2.5.1 Crust This is a solid rock which is the topmost thin layer of the earth’s body, having a solid thickness of about 30 to 40 Km in continents and 5 to 6 Km in the oceans. In fact, it has been concluded that in the continents, the total depth is about 35 Km, out of which the bottom 5 Km depth consists of denser Basalt rock (density of 3.0 g/cm3); and the top 30 Km consists of lighter Granite rock (density of 2.7 g/cm3). The granitic rocks of the continents and the basaltic rocks of the oceans are covered by a top layer of unconsolidated sediments (about 1 Km thick). The earth’s crust provides hard and soft rocks, and is classified as igneous, sedimentary and metamorphic rocks which are to be discussed later. 2.5.2 Mantle This is a region surrounding the heavy core. The mantle consists of upper mantle which is generally solid and the lower mantle which is semi-solid and can flow; and this is the focus of most earthquakes. The crust and the uppermost part of the mantle are relatively rigid and collectively they make up the lithosphere. The lower mantle which is below the lithosphere is called the asthenosphere, which is soft and therefore flows more readily than the upper mantle. It provides a lubricating layer over which the lithosphere moves. 2.5.3 Core This consists of 2 layers (inner and outer core). The inner core is solid and is composed of heavy metals mainly iron (Fe) and Nickel. The outer core consists of the same metals but in a fluid state. Magnetism is generated by the electric currents flowing through the liquid iron (Fe). Therefore the earth has its own magnetic field.
  23. 23. 23 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) http://www.youtube.com/watch?feature=endscreen&v=0mWQs1_L3fA&NR=1 2.6 The Theory of Plate Tectonics The term Plate Tectonics came to be used to denote the process involved in the movements and interactions of the plates (“tectonic” is derived from Greek “tekton”, meaning a builder). Plate Tectonic is a theory that outer shell of the Earth’s surface is divided into large, thick, rigid plates that are slowly moving relative to each other, and changing in size. The plate tectonic theory is a unifying theory that accounts for many seemingly unrelated geological phenomena. Some of the disparate phenomena that plate tectonics explains are where and why we get earthquakes, volcanoes, mountain belts, deep ocean trenches, and mid-oceanic ridges. Plate tectonics regards the lithosphere (crust and upper mantle) as broken into plates that are in motion. The plates, which are much like segments of the cracked shell on a boiled egg, move relative to one another, sliding on the underlying asthensphere (lower mantle). According to plate tectonics, divergent boundaries exist where plates are moving apart; transform/conservative boundary occurs where two plates slide past each other, earthquakes along the fault are a result of plate motion; and convergent boundary occurs where plates move toward each other. http://www.youtube.com/watch?v=1-HwPR_4mP4&feature=related http://www.youtube.com/watch?v=KCSJNBMOjJs&feature=related 2.7 Continental Drift The planet Earth is composed of about six continents namely, Africa, North America, South America, Asia, Europe, and Australia.
  24. 24. 24 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) The continents at one time about 220-250 million years (my) ago, formed one super- continent called “Pangea” or “Pangaea”. Continent drift is the idea that continents move freely over Earth’s surface, changing their positions relative to one another. From the study of magnetism in the rocks of the earth’s crust and from the detailed surveys of the ocean floor; it was concluded in 1960s that continents drifted/drift/move away from one another. 2.7.1 Evidence Supporting Continental Drift 1) Palaeo-climatology: The past climates which are inconsistent with their modern locations. 2) Palaeontology: Patterns of present day animal life, similarities among fossils across continents. 3) Geometric fit of the different continents e.g. if South America and Africa are fitted together, the identical contacts are found in precisely the right position on the shore of South America. 4) Matching Stratigraphy and Truncated structure: The Mountains of North Eastern America, Western Europe and Northern Africa, their compositions are the same and this is a proof that the world was one.
  25. 25. 25 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) 2.8 Sea-Floor Spreading Sea-floor spreading is Hess’s 1962 proposal which is a hypothesis (concept) that the sea floor forms at the crest of the Mid-oceanic ridge, the moves horizontally away from the ridge crest towards an oceanic trench. The two sides of the ridge are moving in opposite directions like slow conveyor belts. Mid-ocean ridges occur along boundaries between plates of Earth’s outer shell where new seafloor is created as the plates spread apart. As plates move apart under the ocean, molten rock, or magma, wells up from deep below the surface of the seafloor. Some of the magma that ascends to the seafloor produces enormous volcanic eruptions. The rest solidifies on the edges of the plates as they spread apart, creating new rocky seafloor material. Formation of an Oceanic Ridge An oceanic ridge develops on the ocean floor where the boundaries of tectonic plates meet. Molten rock is forced up at these boundaries and pushes the oceanic crust up and outward, creating the ridge. Magma Upwelling Mid-ocean ridges occur along boundaries between plates of Earth’s outer shell where new seafloor is created as the plates spread apart. As plates move apart under the ocean, molten rock, or magma, wells up from deep below the surface of the seafloor.
  26. 26. 26 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) Some of the magma that ascends to the seafloor produces enormous volcanic eruptions. The rest solidifies on the edges of the plates as they spread apart, creating new rocky seafloor material. 2.9 Geological Time Scale Geologic time is the time scale that covers earth’s entire geologic history from its origin to the present day. Geology involves vastly greater amounts of time, often referred to as deep time. The earth is estimated to be about 4.55 billion years old. Humans have been here only about the last 3 million years. Geologic time scale helps scientists think about the history of the planet in manageable section of time. Geologists can use fossils in rocks to refer the age of the rock to the standard geologic time scale (below), a worldwide relative time scale. Based on fossil assemblages, the geologic time scale subdivides geologic time.
  27. 27. 27 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) Geologic Time Scale EON ERA PERIOD EPOCH BEGINNINGLIFE FORMS ORIGINATING (YEARS AGO) Neogene Holocene (Recent)…11500…………………………………………… (Quaternary) Pleistocene…………..1.8 million……………Human…………………. Cenozoic Paleogene Pilocene………………5.3 million…………………………………………. (Tertiary) Miocene……………….23 million……………Grazing and…………. Oligocene……………..34 million……………Carnivorous………… Eolene…………………..56 million…………..Mammals………… ………………………….Paleocene………………65 million………………………………………. Phanerozoic Cretaceous…………………………………145 million….Primate, flowering, plant Mesozoic Jurassic…………………………………………200 million……………..Birds………………… Triassic …………………………………………251 million………Dinosaurs, Mammals Perimian…………………………………….299 million……………………………………….. Carboniferous Pennsylvanian…….318 million………………Reptiles……… Paleozoic Mississippian……359 million………..Fern Forests…………. Devonian………………………………………416 million….Amphibians, Insect……. Silurian……………………………………….444 million..Vascular land plants……. Ordovician…………………………………….488 million….Fish, Chordates…………. Cambrian………………………………………542 million….Shell fish, Trilobites…… Proterozoic………………………………………………………………………………..2.5 billion…….Eukaryotic cells……….. Archean ………………………………………………………………………………………… 3.8 billion? ....Prokaryotic cells…….. The geologic time scale, representing an extensive fossil record consists of three eons (Archean, Proterozoic and Phanerozoic). Each eon is subdivided into eras. Each era is made up of periods, which are further divided into epochs. The Archeon and Proterozoic eons are collectively called Precambrian time. Precambrian denotes the vast amount of time that proceeded the Paleozoic era (which begins with the Cambrian period). The Paleozoic era (meaning old life) began with the appearance of complex life, as indicated by fossils. Rocks older than Paleozoic contain few fossils. This is because creatures with shells or other hard parts, which are easily preserved as fossils, did not evolve until the beginning of the Paleozoic. The Mesozoic era (meaning middle life), followed the Paleozoic. We live in the recent (or Holocene) epoch of the Quaternary (or Neogene) period of the Cenozoic era (meaning new life).
  28. 28. 28 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) CHAPTER THREE The Lion looked at Alice wearily. “Are you animal – or vegetable – or mineral?” He said, yawning at every other word. Lewis Carroll (1832 - 1898), British writer and mathematician. 3.0 MINERALOGY 3.1 INTRODUCTION Mineralogy is the study of minerals. Minerals are the basic constituents of rocks, and thus influence the properties of the rocks. A mineral is a naturally occurring homogeneous solid with a definite chemical composition and highly ordered atomic arrangements. A mineral is a body produced by the process of nature, having a definite chemical composition and, if formed under favorable conditions, a certain characteristic, molecular structure which is exhibited in its crystalline form and other physical properties.  Definitions  Summarized Ugandan Minerals Inventory and their uses.  Identification of Minerals and their properties.  Physical properties  Microscopic Optical properties  Chemical properties SUMMARY
  29. 29. 29 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) 3.2 SUMMARISED UGANDA MINERAL INVENTORY AND THEIR USES Map of Uganda showing all districts
  30. 30. 30 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com)
  31. 31. 31 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) ITEM MINERAL COMMODI TY DISTRICIT LOCATION USAGE 1 Aggregates and Crushed Stones. All Districts Construction of Houses, Roads and other Civil works. 2 Asbestos Arua Anzaiya Roofing, Brakes and Friction, Ceramics, Chemicals and Fertilizers, Paint, Coatings Vanish, Gaskets, Insulation Mats. Moroto Morungore Nakapiripirit Nakiloro 3 Beryllium Busheny Kaharoro, Murali, Mutaka. Beryllium – Copper Alloys with great fatigue resistance nuclear field, Aeronautic Industry. Mbarara Kihanda Mukono Lunya Rukungiri Bugangari, Bulema, Kyanymphiha, Ishasha, Nyabushoro, NyabuKarina. 4 Bismuth Rukungiri Muramba, Kayonza, Rwanzu, Kyambeya, Kitwa, Rwenkuba, Kitawulira. Medical, Cosmetic, Low – Melting point alloys when combined with Lead, Tin, Cadmium and Antimony, Bearing Alloys with Brass and Bronze.
  32. 32. 32 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) 5 Chalcopyrite Kasese Kilembe Copper wires, Coins, Alloys like Brass and Bronze production. Copper Salts used in Industries like treatment of Timber and Fungicide. 6 Kyanite Rukungiri Ihunga Hill Nebbi Azi 7 Clay Widely spread in the country close to swamps river valleys and rift valleys. Bricks, Tiles Ceramic Ware. 8 Cobalt Kases Kilembe Used in the form of Ferrous and Non – Ferrous Alloys, special Steels, also as the oxide and in Salts, Glass and Ceramics, Chemical and Bio Chemical Industry. 9 Copper Kasese Kilembe Wide applications in Electrical and Metallurgical Industries. Karamoja 10 Chromites Moroto Nakiloro Manufacture of Metallurgical products, Refractory used in Metallurgical Plants. Cements and Plastics used in the construction of Furnaces, Chemical Products such as Chromates and Pigments. Kitgum Burukung and Abora Rivers. 11 Diatomite Nebbi Panyango, Alui, Atar. Chemicals and Fertilizers, Filter Medial e.g. Brewing Industry, Ferrites, Insecticides, Herb/Fungi.Pakwach 12 Feldspar Mukono Lunya Ceramics, glass, Glazes, enamels, pottery, poultry grit. Bushenyi Mutaka 13 Glass Sand Masaka Bukakata, Diimu. Glass ware, Enamel ware, Refractories, Scouring and Polishing Media, Plastics, Rubber, Dental Products, Construction etc.Wakiso Entebbe Mpigi Nalumuli, Kome Island Mukono Nyimu 14 Graphite Kitugum Omia, Orom Hills Lead pencils, Batteries Crucibles, Finer Grade used as Lubricant. Nebbi Zeu Moroto Ekuyen 15 Gold Bushenyi Mashonga, and Buhweju.
  33. 33. 33 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) Busia Amonikakinei, Makina, Alupe, and Nanguke. Jewellery and Decorative, Electronics, Bullion, Monetary, Dental, Medical, and Industrial Supplies. Mbarara Ibanda, Mabonwa – mpasha, Rukiri, and Katenure. Kanungu Kanungu Moroto Rupa Kotido Lopedo, and Alerek. Arua Most Streams at DRC Boarder. Nebbi Nyagak River, Goli hill. Bugiri Bude – Kitojha. Moyo Most Streams at Sudan Boarder. 16 Gypsum Mbarara Mburo Ceramics, Glass, Glazes, Enamels, Chemicals Cement Manufacture, Building wall and Wall Board, Soil Container, Textiles, in Casting and Moulds. Bundibugyo Kibuku Kasese Muhokya 17 Nickel Mbarara Kajunzo Ntungamo Rugaga 18 Kaolin Bushenyi Mutaka Ceramics, Chemicals, Construction, Glass, Glazes, Enamel, Insecticides, paint, coatings, Vanish, Paper, Leather Tanning, Refrectories, Welding Electrodes. Rakai Kisai (Koki) Moyo Lunyenye Nebbi Kuluva 18 Lead/Galena Kabalore Kitaka Used in Battery manufacture, Low Melting point Alloys, Paint, and Glass. 20 Lime Stone Kasese Hiima Cement, Lime, Ceramics, Chemicals and Fertilizers, Lime used in Soil Stabilisation, Water Treatment, Poultry and Animal Feed stuffs.Tororo Tororo Hiill Mbale Bukiribo Moyo Gweri Hill Kabarole Dura 21 Lithium Mubende Used in Glass Industry, Enamels, Fluxes, Greases, Bleaches. Kabala 22 Magnetite Moroto Lolung Making Rubber, Stucco, Magnesium, salts, Heat Insulation Metallurgy and Refractories.
  34. 34. 34 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) 23 Marble Kotido Cement, Terrazzo, Dimensional Stone. Moyo Moroto Forest Reserve, Tank Hill, Rupa, Katike Kakile. 24 Malachite Kasese Kilembe Minor ore of Copper used as Ornamental and Gemstone. 25 Mica Arua Chere River Electrical and Heating Insulation e. g. in Flat – Iron, Welding Electrodes, Plastics and Rubber, Cosmetic and Pharmaceuticals.Kotido Labwor and Morulem Nebbi Aguyi and Aliakira Kitgum Orom, and Pailma. Mukono Lunya. 26 Niobium (Columbium ) Tororo Sukulu Useful for its corrosion resisting properties at high temperature such as in Superchargers and Gas Turbines, in Mild and Stainless Steels, used in Dyes for Artificial Fibres. Rukungiri Bulema Kanungu 27 Phosphate Mbale Busumbu Fertilize and Chemicals based on elemental Phosphorus and Phosphoric Acid, Livestock Food.Tororo Sukulu 28 Precious Stone Karamoja Ornamental 29 Pyrite Kasese Kilembe Manufacture of Sulphuric Acid, as a Gemstone old as Marcasite. 30 Salt Kasese Lake Katwe Source of common salt (Sodium Chloride) and a wide range of other salts e. g. Sodium Carbonate and Bicarbonate, Potassium Chloride, Sodium Sulphate, Potassium Bromine; Eutectic Brine, Bromine Gas, used in preservation of Foods, Medicines, and Weed killer. Masindi Kibiro 31 Talc Kasese Kisinga Cosmetic and Pharmaceuticals, Paper, Carpet backing Ceramics, Paint, and Refractories.Bushenyi Kyamuhunga Moroto Lolung 32 Tantalum Rukungiri Very high corrosion resistance and therefore a substitute for platinum in Chemical apparatus Surgical Steels, used in Dyes for Artificial Fibres. Bushenyi Mubende 33 Tin (Cassiterte) Mbarara Kikagati – Kitezo, Ruhama, Ruzinyo. Tin metal, Alloys, Tin Plating, Canning, Utensils, Textile Dying, Ceramic Industry, and manufacture of Solders. Kabale Ruhuma, Buvama, Kamwezi.
  35. 35. 35 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) Ntungamo Kyamugasha. Kanungu Bushenyi Kaina and Rwentobo. 34 Tungsten Wolframite Rakai Buyaga Main use is in high – speed outing tools, Military hardware (Amour Plate), Electric Light Filament, Electrical Contacts and Tungsten Carbide. High speed cutting Tools, Steel, Valves, Springs, Armour Plates and manufacture of resistant Non – Ferrous Alloys. Kabala Nyamulilo, Mpororo, Rushanga, Ruhizha. Masaka 35 Diamond Bushenyi Buhweju 36 Travertine (Lime Stone) Kabalore Dura Manufacture of Decorative Terrazzo, Concrete blocks, Ceramics, Cement, Lime Stone, used in soil Stabilisation, Paints, Water Treatment, Fertilizer, Building White Wash, Stone, Road Metal, Whiting substitute and Paper Mills, Neutralization of Waste Acid, Waste Treatment, Poultry and Animal Feed Stuff. 37 Vermiculite Mbale Namakhara, Sukusi, Kabatola, Surumbusa, Nakhupa. Used in Heat and Sound Insulation, Insecticides, Light weight Bricks, Building Plaster, Lubricants, Brake Linings and Soil Conditioning. 38 Water Widely spread in the Country except in the in the Rift Valley. Drinking. 39 Zircon Moroto Rupa Gemstones, Refractory and source of Zirconium Oxide used in the manufacture of Incandescent Gas Mantles and Abrasive. 40 Iron Ore Mbarara Mugabuzi Roofing Sheets, Iron Bars, and Iron ore is added to Scrap material in Steel production at Jinja.Kabala Butare (Muko) Tororo Sukulu Kisoro Kyanyamuzinda Moyo Gweri (Metuli) Iganga Wambogwe.
  36. 36. 36 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) 3.3 Identification of Minerals and their Properties Every individual mineral has a certain set of properties, which will be characteristic of that mineral alone. By testing a mineral for all such properties, therefore, we can easily identify it. The various properties of the minerals, the study of which may help in their identification are:- 1. Physical properties 2. Microscopic optical properties 3. Chemical properties 3.3.1 Physical Properties of Minerals The physical properties of minerals are important aid in identifying and characterizing them. The various physical properties of minerals are: - streak, colour, luster, hardness, cleavage, fracture, tenacity, specific gravity, etc. Colour The first thing most people notice about a mineral is its colour. For some minerals, colour is a useful property. Muscovite mica is white or colourless. Most naturally occurring minerals contain traces of substances which modify their colour. Thus Quartz, which is colourless when pure, may be white, grey, pink, or yellow; when certain chemical impurities or included particles are present. Streak The streak of a mineral is the colour of its powder. The streak of a mineral can be readily observed by scratching it on a streak plate, which is made up of unglazed porcelain or roughened glass. Streak plate has a hardness of about 7.0 and cannot be used for minerals of greater hardness and transparent minerals. While determining streak for a mineral, care should be taken to scratch it from its obscure part, and to give only a small scratch, producing a small quantity of its powder. Streak is useful, e.g. in distinguishing the various oxides of iron like: - hematite (Fe2O3) gives a red streak; Limonite (hydrated Fe2O3) gives a brown streak, and Magnetite (Fe3O4) gives a grey streak.
  37. 37. 37 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) Luster The shine of a mineral is called its luster. Luster can also be defined as the appearance of a mineral surface in reflected light. The luster of a mineral is described by comparing it to familiar substances. Different Types of Luster No Type of Luster Represented by Mineral examples 1 Vitreous Luster A mineral having a glassy shine Quartz and Calcite 2 Pearly Luster A mineral having a pearly shine Muscovite 3 Metallic Luster A mineral with a metallic shine Magnetite 4 Silky Luster A mineral with a silky shine Asbestos 5 Resinous Luster A mineral with a greasy shine like that of a resin Talc 6 Adamantine Luster The mineral having a diamond like shine Diamond and Zircon Cleavage Cleavage is the ability of a mineral to break, when struck along preferred direction. The planes along which the crystal breaks are called the cleavage planes. A mineral tend to break along certain planes because the bonding between atoms is weaker there. In Quartz, the bonds are equally strong in all directions; therefore, Quartz has no cleavage. The Micas, however, are easily split apart into sheets. Terms used to describe cleavage include: - perfect, good, distinct, imperfect and no cleavage. Different Types of Cleavage No Type of cleavage Represented by Mineral Example 1 Basal cleavage There are one set of cleavage. The crystals with this cleavage can easily break or split into thin sheets. Muscovite 2 Prismatic cleavage There are two sets of cleavage. The cleavage planes are parallel to the vertical set of crystal faces. Hornblende
  38. 38. 38 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) 3 Cubic cleavage There are three sets of cleavage at right angles to each other. Galena 4 Rhembohedral cleavage There are three sets of cleavages directions, each excellent but at angles other than right angle. Calcite 5 Octahedral cleavage There are four sets f cleavage. The cleavage planes are parallel to the faces of the crystal form. Fluorspar and Magnetite. Fracture This is the appearance or nature of a broken surface of a mineral when it is hammered and broken. The break being irregular and independent of cleavage; a fresh fracture shows the true colour of a mineral. Different Types of Fractures No. Type of Fracture Represented by Mineral Example 1 Even Fracture When the broken surfaces of a mineral is smooth. Chert 2 Uneven Fracture When the mineral breaks with very rough and coarse surface. Chromite and various other minerals. 3 Hackly Fracture When a mineral breaks with irregular surfaces having sharp edges. Native Copper 4 Earthy Fracture When the broken surface is soft and almost smooth. Chalk 5 Conchoidal Fracture When a mineral breaks with curved surfaces. There will be concentric grooves and ridges resembling with the concentric lines of growth on a shell. Quartz
  39. 39. 39 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) Tenacity The response of a mineral to a hammer below, to cutting with a knife and to bending is described by its tenacity. Different types of Tenacities of Minerals No. Type of Tenacity Represented by Mineral Example 1 Sectile When the mineral can be cut with a knife. These are very soft minerals. Talc and Graphite 2 Malleable When a mineral flattens into a sheet, when hammered. It can also be cut with a knife as sectile mineral. Silver and Gold 3 Brittle When a mineral crumbles to grains or powder, when hammered. Most of the minerals are brittle in nature. Quartz, Fluorite, Calcite, Magnetite, etc. 4 Flexible When a mineral can be easily bent. Chlorite 5 Elastic When a flexible mineral on being bent, does regains its original position, as the bending force is removed. Muscovite and Biotite 6 Inelastic When a flexible mineral on being bent, does not regains its original position, as the bending force is removed. Gypsum Specific Gravity (Gs) Specific gravity of a substance is the ratio of its weight to the weight of air equal volume of water at 4oc. H20 has Gs of 1.0. To determine this, property, a balance can be used, for crystals or fragments which are not too small. The mineral (or rock) is weighed in air and in water, and the specific gravity, Gs, is calculated from the formula: W1/ (W1-W2), where W1 = weight in air and W2 = weight in water.
  40. 40. 40 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) Mineral possessing heavier and closely spaced atoms will have high Gs; whereas, a mineral possessing lighter and widely spaced atoms will have a low Gs. The Gs of the mineral is thus, a representation of its atomic structure. Light Gs<2:0, Normal Gs = 2 to 4, Heavy Gs= 4 to 6, extremely heavy Gs>6 Specific gravity of common minerals Mineral Specific gravity Hematite 4.9 - 5.3 Magnetite 5.17 Hornblende 3.2 - 3.5 Kugite 3.2 - 3.4 Biotite 2.8 - 32 Micas 2.7 – 3.1 Muscovite 2.7 - 3.1 Chlorite 2.6 - 2.9 Dolomite 2.85 - 2.87 Calcite 2.72 - 2.90 Talc 2.70 - 290 Sermentive 2.20 - 2.70 Quartz 2.65 Cypsum 2.32 Feldspar 2.56 - 2.7 Hardness Hardness of a mineral may be defined as the resistance which the mineral offers to scratch. This property of a mineral is generally determined by scratching a given mineral with a mineral of known hardness, so as to obtain the comparative figure for the hardness of the given mineral.
  41. 41. 41 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) Moh’s scale The Moh’s scale is used to rate the relative hardness of a material by performing scratch test and hardness, or resistance to abrasion, is measured relative to a standard scale of ten minerals, and known as moh’s scale of hardness as seen below. These minerals are chosen so that their hardness increases in the order 1 to 10. Moh’s Scale of hardness Hardness H Mineral 1 Tale Can be scratched with a finger nail. 2 Gypsum 3 Calcite Can easily be cut with a pen knife or scratched by copper coin 4 Fluorspar Can easily be scratched with a knife blade or window glass 5 Apatite 6 Feldspar Can be scratched with a pen knife but with difficulty 7 Quartz Scratches a knife blade or window glass cannot be scratched with any ordinary Implement. Quartz will scratch glass; topaz will scratch quartz will scratch quartz; corundum will scratch topaz and Diamond will scratch corundum 8 Topaz 9 Corundum 10 Diamond The numbers given are used as relative hardness numbers, relative only since the actual hardness value of talc is about 0.02, whereas that for a diamond runs into the thousands. Other miscellaneous properties Besides the above physical properties of minerals, there are others like: a) Transparency (minerals capability to pass light through it) b) Fluorescence (is due to which mineral may emit light when exposed to radiations like x-rays). c) Phosphorescence ( is due to which mineral may emit light after it has been exposed to certain radiations or subjected to heating or rubbing)
  42. 42. 42 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) d) Taste, feel, odour (all depending upon the senses); fusibility (depending on heat), magneticity (depending upon the magnetic capability) electrical conductivity (such as good conductor or bad conductor) 3.3.2 Microscopic Optical Properties of Minerals Apart from physical properties of mineral, there are several other characteristics of mineral, which can be studied under a polarizing microscope. These properties, known as optical properties, help in more precise identifications of even minute grains of minerals. This helps in the identification of rocks, which are just nothing but aggregates of different minerals. How to prepare a Rock Slice A thin section of the given mineral called the slide/Slice has to be first of all, prepared, before it can be tested under a polarizing microscope. Equipment: 1. Grinding wheels 2. Glass or steel plates 3. Abrasive powders (commonly Carborundum powders) of various course and fine grades 4. Hot plates 5. Canada balsam 6. Glass strips 7. The cover slips 8. Methylated Spirit Procedures  A chip of rock (or slice cut by a rotating steel disc armed with diamond dust) is smoothed on one side and mounted on a strip of glass 75 x 25mm.  The specimen is cemented to the glass strip by means of Canada balsam, a gum which sets hard after being heated, or a synthetic resin.  The mounted chip of rock is then ground down with Carborundum and emery abrasives to the required thinners, general 30µm (1 micrometer = 1/1000millimeter)
  43. 43. 43 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com)  The transparent slice is completed by covering it with a thin glass strip fixed with balsam.  Surplus balsam is washed off with methylated spirit. The surface of the specimen has been smoothed in making the slice/slide, and they are free from all but very small irregularities. Note: At this stage, the specimen is ready for being studied under the Microscope. Instruments and processes involved in optical mineralogy.  A polarizing microscope, also called a Petrological Microscope, is the most important instrument which is used in any study dealing with the process of determining the optical properties of minerals.  A polarizing microscope essentially consists of:- a) a Reflecting mirror at the base, b) A Nicol prism (called the polarizer) between the mirror and the stage;
  44. 44. 44 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) c) An objective above the stage d) Another Nicol prism called the (analyzer) above the objective. e) An eye- piece  The eye-piece, the analyzer and the objective are fitted into an adjustable tube, which can be raised or lowered with the help of coarse (focusing) and fine adjustment screws.  The polarizer also be raised or lowered with the help of its own adjuster  Such a Polarizing/ Petrological microscope is used to study the optical properties of the given mineral.  The prepared slide of the sample is now placed on the stage of the microscope, and studied for its optical properties.  The main optical characteristics are studied using polarized light and these include Refractive index, Pleochroism, Extinction, Interference colours and Opaque minerals.  Besides studying the main optical characteristics, the slide can be used to study some general physical properties like colour, cleavage, shape, form, e.t.c of the minute grains of the mineral, under the microscope, using ordinary light and without using the polarizer and analyzer. 3.3.3 Chemical Properties of Minerals 3.3.3.1 Rock forming Minerals The minerals which constitute the bulk of the rocks of the earth’s crust are called the rock forming minerals. Civil engineers are more concerned with the rock forming minerals because they need to know the properties of the rocks precisely, to enable them to consider different rocks for their civil engineering uses, like: picking the rocks as good foundations, or for using the rocks for making concrete aggregates, as building stones, or road metal, or flooring, roofing, or decorative materials, etc. Since the properties of rocks will mainly depend upon the properties of their constituent minerals, a detailed study of the rocks forming minerals becomes imperative for all the civil Engineers. The study of the minerals, constituting a rock, will help him/her to identify the rock with reference to their appearance, strength, durability, etc.
  45. 45. 45 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) 3.3.3.2 Classification of Minerals Minerals can be classified as:- a) Silicate Minerals b) Non-Silicate Minerals c) Clay Minerals A) Silicate Minerals The existence of a silicon tetrahedron makes a mineral as silicate mineral. 1. Felspar/ Feldspar group Felspars are the most abundant silicate mineral, in which the silicate tetrahedrons are arranged in a three dimensional frame work, e.g feldspars and Quartz. Types i) Felspars These are identified by their hardness (6.0), 2 cleavages at nearly right angles (85o to 86o) Gs 2.76 and light colours (such as white, pink, grey, etc). They are the most important constituents of igneous rocks. Examples include:-  Plagioclase felspars, also called sodic felspars or soda lime felspars;  Potassium felspars also called potash felspars or orthoclase felspars. ii) Quartz (Silca or silicon- dioxide SiO2) Pure Quartz is white, but due to impurities it may have any colour, such as black, pink, yellow, e.tc. Its other characteristics are:- Vitreous luster, no streak, no cleavages, hardness = 7.0, specific gravity = 2.65, and conchoidal fracture. Under microscope, Quartz grains are found to have low refractive index and positive optical sign. Quartz occurs in a number of varieties, such as low quartz, high Quartz, Tridymite, and cristobalite, chalcedony, Agate and Jasper. 2. Pyroxene group or pyroxenes. Pyroxene is a silicate mineral’s family, in which the tetrahedrons are arranged in single chains that are held together by other positive ions, such as calcium, Magnesium and Iron. Pyroxenes can be represented by the chemical formula: RSiO3, where R represents
  46. 46. 46 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) Ca, Mg, Fe, etc. They are generally recognized by dark colours, hardness (5-6), and 2 cleavages that meet at nearly right angles (93o or so) Types a) Orthorhombic pyroxenes, which include - Enstatite (Mg. SiO3) - Hypersthene (Fe.Mg.SiO3) b) Monoclinic pyroxenes, which include - Clino- enstatite (Mg.SiO3) - Diopside- Hedenbergite (Ca, Mg (SiO3)2) and (CaFe (SiO3)2); - Augite, a complex silicate (Mg, FeII, FeIII, Al) (Si Al) 2 O6) - Aemite (NaFe (SiO3)2) - Spodumene (LiAl (SiO3)2) - Jadeite (NaAl(SiO3)2); e.t.c c) Tricline pyroxenes; which include - Rhodonite (MnSiO3) and Babingtonite. Augite It is characterized by: black - dark green colour, vitreous luster, no streak, two directional distinct prismatic cleavages at an angle of about 90o, Gs = 3.2 -3.5, hardness = 5.0 to 6.0. Its main use is its occurrence as an important rock forming mineral, which occurs in many basic igneous rocks, and also in metamorphic rocks like Gneisses and Granulites. A few lustrous varieties of Augite are used as gem stones. 3. Amphibole group or Amphiboles In this group, the silica tetrahedrons are arranged in double chains. Amphiboles exhibit cleavage in two directions at an angle of about 120o. Examples a) Orthohombic Amphiboles, which include: - Anthopyllite (CMg.Fe) SiO3), etc. b) Monoclinic. Amphibole which include:  Cummingtonite Grunerite (Fe, Mg, Silicate)  Tremolite (Ca, Mg3(SiO3)4),  Hornblende (Ca2Na(Mg FeII)4 (AlFeIIITi)(Alsi)8 022(O,OH)2)
  47. 47. 47 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com)  Actinolite (Ca(Mg, Fe3) (SiO3)4)  Glaucophane (Fa, Fe, Al, Silicate)  Riebeckite (Na, Fe, Silicate) c) Triclinic Amphiboles, which include: Aenigmatite Hornblende It is characterized by: black, dark-green colour, vitreous luster, no streak, 2 directional distinct cleavages at an angle of about 120o, Gs = 2.9 to 3.4, hardness = 5 to 6. Hornblende occurs mainly in acidic igneous rocks, and is used in the manufacture of cement. 4. Mica Group or Micas Micas are complex hydrous silicates of metals like potassium (K), Magnesium (Mg), iron (Fe), etc. In all Micas, the silica tetrahedrons are arranged in sheets or layers thus giving a clear cut sheet like formation or structure to these minerals. Due to this type of structure, Micas will cleave, separating into thin flexible layers. E.g. Chlorite, Serpentine, Talc, Biotite, Muscovite or Potas Micas Examples a) Biotite, Biotite is the name given to black Mica, and is represented by the chemical formula (K(Mg Fe)3 (AlSi3 O10 (OH)2) It is characterized by deep brown to black colour, vitreous pearly luster, no streak, hardness = 2.5 to 3, sheet structure, perfect cleavage with the capability to split into exceedingly thin sheets in one direction. Gs. = 2.8 to 3.0, no fracture e.t.c Biotite is found in many igneous rocks and metamorphic rocks. It is used in light weight concrete. b) Muscovite or Potas Micas Muscovite is the name given to white mica and is represented by the chemical formula (KAl2 (AlSi3O10) (OH) 2). It is characterized by white colour, vitreous to pearly luster, no streak, hardness = 2 to 2.5, sheet structure, perfect cleavage with the capability to split into exceedingly thin sheets in one direction, Gs = 2.7 to 2.9, even fracture e.t.c
  48. 48. 48 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) Muscovite usually occurs in igneous rocks like in Granites and pegmatite, and also in metamorphic rocks like schist. Many sedimentary rocks also contain muscovite. Muscovite is used as an insulating material in electrical instruments. B) Non- Silicate minerals These are minerals that do not contain silica tetrahedrons. Important Non- Silicate Minerals No Chemical group General Name Chemical Name Chemical Formula 1 Oxides Hematite Iron oxide (ferrous) Fe2O3 Magnetite Iron oxide (Ferric) Fe3O4 Liminite Hydrous Iron oxide Fe2O3 A H2C Chromite Oxide of iron and chromium Fe.Cr2 O4 Corundum Aluminium oxide Al2O3 Bauxite Hydrated Alminium oxide Al2O3.2H2O 2 Carbonates Calcite Calcium carbonate CaCo3 Dolmite Calcium Mg. carbonate Ca,Mg (Co3)2 3 Sulphides Pyrite Iron sulphide FeS2 Chalcopyrite Copper iron sulphide CuFes2 Cinnabar Mercury sulphide Hgs Galena Lead sulphide Pbs Sphalerite Zinc sulphide Zns 4 Haloids Halite Sodium chloride Nacl Fluorite Calcium fluoride CaF2 5 Sulphates Brite Barium sulphate BaSo4 Gypsum Calcium sulphate (hydrous) CaSo4.2H2o Anhdrite Calcium sulphate(anhydrous) CaSo4
  49. 49. 49 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) C) Clay minerals: These have properties that are of great importance to Geotechnical Engineers, Some clays swell when wet and shrink when dry. Such clays can cause settlement in foundation of structures and roads. Gs of clay = 2.60 to 2.90. Most of clay minerals are soft and exhibit plasticity when mixed with a limited quantity of water. Particle sizes (<0.002mm).e.g. – Kaolinite, Halloysite (amorphous), Montmorillonite, Beidellite, Pyrophyllite, Allophane, Illite (hydro mica), chlorite, Bentonite clay, china clay (Kaoline), Ball clay Kaolinite Kaolinite is a clay mineral used as a raw material in the manufacture of pottery and porcelain, filler in rubber, paint and paper industry.
  50. 50. 50 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) CHAPTER FOUR Matthew 16:18 Jesus Christ said “Now I say to you that you are Peter (which means ‘Rock’), and upon this Rock I will build my church, and all the powers of hell will not conquer it. 4.0 PETROLOGY 4.1 Definitions The term petrology is derived from the Greek word, Petro +Logos. Petro means rocks and logos mean study. Hence, petrology means the study of the rocks. Petrology deals with the study of mode of formation, structure, texture, composition, occurrence, types, and e.tc of the various rocks of the Earth’s crust. Rocks are the aggregates of minerals, including hard as well as soft materials, like stones, sands, clay, e.t.c 4.2 Rock Cycle The rocks of the Earth’s crust are of 3 types;- - Igneous rocks - Sedimentary rocks - Metamorphic rocks The Igneous rocks are prime most rocks which solidify from a molten mass, called magma. These rocks are formed below the Earth’s surface as well as on the Earth’s  Definitions  Rock Cycle  Types of Rocks  Igneous Rocks  Sedimentary Rocks  Metamorphic Rocks SUMMAR
  51. 51. 51 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) surface. The ones formed below may be exposed by their continued erosion caused by water, oxygen, carbon dioxide and temperature changes. These rocks are attacked and disintegrated by these external agents of weathering (the collective process of rocks disintegration and decays). When these rocks have been weathered into loose material, they are subjected to removal by wind, water, ice, or organisms. After moving some distance, these loose sediments may again come to rest, and thus get deposited over other rocks in layers, forming what are called as the sedimentary rocks/ stratified rocks. Once having formed from a molten mass (i.e Igneous rocks) or through the process of sedimentation or stratification (i.e. sedimentary rocks), a new environment of heat, pressure or both generally in the presence of hot fluids such as water, may be imposed upon these rocks and thereby changing them into a third type of rocks, called the metamorphic rocks. These metamorphic rocks can be further subjected to over powering stresses and heat, which may cause the melting of metamorphic rocks, giving rise to new igneous rocks. The sequence of events, described above, constitutes what is known as the rocks cycle.
  52. 52. 52 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) 4.3 Types of Rocks As mentioned earlier, there are three types of rocks namely:- a) Igneous rocks b) Sedimentary rocks c) Metamorphic rocks 4.3.1 Igneous Rocks (Eruptive Rocks) 4.3.1.1 Formation of Igneous Rocks Igneous rocks or eruptive rocks are formed when magma (natural hot molten material or liquid rock, probably existing below the Earth’s surface) erupts out on or within the Earth’s surface due to volcanic activities.
  53. 53. 53 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) 4.3.1.2 Mode of occurrence of Igneous Rocks Igneous rocks may occur in two ways, either as intrusive bodies (i.e. large rock masses which have not formed in contact with the atmosphere), or as extrusive bodies (i.e. those rocks which occur above the surface of the Earth). These intrusive and extrusive bodies may occur in different forms depending upon factors, such as, the capability and strength of Magma; the type, texture and strength of adjoining rocks, etc. The various forms in which these intrusive and extrusive igneous rocks may occur are explained below. 4.3.1.3 Forms of Intrusive Rocks (Plutonic Rocks) Intrusive rocks occur when magma is unable to disturb and cut across the existing intruded rocks, it may get cooled and solidified within the fissures and cavities prevailing in the existing rocks. Intrusive rocks may occur in different forms, such as: - Sills, Phacoliths, laccoliths, Dykes, Batholiths and volcanic neck. 1. Sill. Occurs when the magma is pushed into the existing bedding layers of the intruded rocks; and solidifies there, in the form of a thin sheet. Rock A Sill Rock B 2. Laccoliths. Occurs when magma injects into the layers of the intruded rocks, but is unable to spread length and width wise for greater distances due to high viscosity, it may force the layers of rocks upwards, in the form of a dome or an arch. Intruded rocks arching up Laccoliths
  54. 54. 54 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) 3. Dykes. Occurs when the magma is forced through the vertical or nearly vertical cracks or fissures in the intruded rocks and is consolidated there as a wall like structure. Dyke Rock A Rock B Rock C 4. Batholiths. This occurs when the magma moving under high pressure fills up a large space in the pre-existing intruded rocks by melting them away or keeping them aside, or by any other means; thus forming a huge mass of igneous rock. Rock A Rock B Rock C Batholiths 4.3.1.4 Forms of Extrusive Rocks (Volcanic Rocks) These are igneous rocks that crystallize on the surface of the earth. The magma is poured out at the surface. They undergo rapid cooling such that there is no enough time to form large crystals. Their texture is glass like. They occur in two major forms:- 1. Flow or Lava flows
  55. 55. 55 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) Flows are identical to sills in their external appearance, because when lava oozes out, it will spread over the surface in thin sheets, getting consolidated there. 2. Pyroclastics. These are all associated with volcanism and represent rock fragments blown out of volcanoes during eruptions. They are classified according to size and include:-  Volcanic bombs (include materials from a few centimeters to meters in diameter)  Cinders (include materials from 5mm to several centimeters in diameter)  Tuffs (include materials less than 5mm in diameter)  Volcanic ash (is the finest dust particles which remain suspended in the atmosphere for months together before settling down on the earth). 4.3.1.5 Classification of Igneous Rocks 1. Plutonic rocks. Intrusive igneous rocks formed at great depth a) Granites, b) Syenites, c) Gabbros d) Peridotities, e) Diorites 2. Hypabyssal rocks: are intrusive igneous rocks formed below the surface of the earth but at a short distance, e.g. Dolerites 3. Volcanic rocks: - These are extrusive igneous rocks formed over the earth’s surface a) Rhyolites b) Andesites c) Basalts Granites Granites are light coloured rocks of plutonic origin. Their colours are grey, pink or red and depend chiefly upon the colour of the feldspar mineral present in a particular Granite. They are acidic in nature, with Quartz and feldspar as essential minerals. Texture: Granites are generally of coarse-grained texture and sometimes of medium- grained textures. Types: Granites are named after prominent presence of a particular accessory mineral like Hornblende Granite, Biotite Granite, Tourmaline Granite, Augite Granite, Muscovite Granite e.t.c Mode of occurrence: Granites commonly occur in the form of large igneous bodies, like batholiths. May also occur in the form of large igneous bodies, like batholiths; also may occur in the form of dykes.
  56. 56. 56 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) Physical properties and uses: They have a very high crushing strength (100 to 250MN/M2); low water absorption value (0.5-1.2%); least porosity (very low); Specific gravity (2.6 to 2.8); Density (2500 to 2650Kg/m3); Hardness (very hard with Hardness coefficient as 18); Frost and fire resistance (Good frost resistance but low fire resistance). Granites are extensively used as building stones for structural as well as decorative, monumental and architectural purposes. They can take fine polish and are the strongest available stones. They can also be used as road aggregates and concrete aggregates. Dolerites These are hypabyssal igneous rocks, dark (such as grey or black) in colour. They chiefly consist of calcic plagioclase felspars, such as, Labradorite and Anorthite. The ferromagnesian minerals generally present are olivine, Augite and iron oxides. Textures: Dolerites have fine-grained texture. Mode of occurrence: Dolerites commonly occur as sills and dykes. Properties and uses: They are highly tough and possess high abrasion resistance. They are not used as building stones but are generally used as crushed stones for concrete aggregates and for making road. Andesites They are light coloured volcanic rocks. The essential minerals are felspars. Texture: They are generally fine-grained aphanitic rocks. Types: These include. Hornblende Andesite and Biotite Andesite base on the presence of prominent quantities of accessory minerals, such as Hornblende & Biotite. Mode of occurrence: They are the most abundant volcanic rocks, but next to Basalts. They occur in the form of lava flows of huge dimensions. Properties and uses: Like all volcanic rocks, they are not of much use as dimension stones. They may be used as crushed stones. 4.3.2 Sedimentary Rocks/Stratified/Secondary Rocks It is called Stratified rock because sediments are deposited and consolidated in layers. It is called Secondary rock because it is formed from some existing primary rocks.
  57. 57. 57 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) Sedimentary rocks are formed by the deposition and consolidation of new sediments (loose or solid particles), in layers, over the pre-existing rocks. The sediments are eroded away from some old rocks by weathering and are then transported by agents like wind, water, ice, etc. The eroded sediments, after traveling, may get deposited over some existing rocks, which on consolidation will form sedimentary rocks. About 75% of the rocks on earth’s surface are sedimentary in origin. 4.3.2.1 Formation of Sedimentary Rocks The sedimentary rocks are formed in the following four different stages:- i) Weathering (i.e. erosion of the existing rocks) Mechanical weathering disintegrates a pre-existing rocks into smaller fragments and chemical weathering acting on these small fragment, rearranges the elements into new minerals and thus decomposes them. ii) Transportation of Eroded sediment. The products of rock weathering are generally transported in large amount by the running waters (i.e. rivers), moving ice (i.e. glaciers), and blowing winds. iii) Deposition of Eroded Sediment The transportation of the weathered products continues as long as the velocity of the transport of medium remains unchecked. But when these products are brought at rest into big water bodies like oceans and lakes, their deposition will start. Of the weathered products carried in suspension, the coarser and the heavier pieces will settle first, followed by lighter and finer particles. The weathered products carried in solution may precipitate out at a later stage, which may form a separate layer on deposition. iv) Lithification of Deposited sediment. The transformation of loosely deposited sediments into a rock is called lithification. This can be done in 2 ways:- a) By compaction or consolidation: As deposition of sediment continues, it automatically goes on compacting and consolidating due to its own weight with the squeezing out of water.
  58. 58. 58 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) b) By cementation: Water soluble materials, such as calcite, silica, iron oxides, dolomites, clay, e.t.c; are deposited by ground water, between the various grains of the deposited sediment thus bonding them together. 4.3.2.2 Classification of Sedimentary Rocks Sedimentary rocks can be divided into three categories i.e. 1. Clastic rocks The word clastic means fragmental. Clastic rocks are derived from fragments or individual minerals of other rocks. E.g. Breccias, conglomerates, sandstones, shale, Boulders, cobbles, Pebbles or coarse gravel, Gravel or Granules, sand (coarse and fine), silt and clay. 2. Chemical sediments/Chemically formed sedimentary rocks These are rocks formed when weathered materials which travel in solution and reach the water bodies such as lakes and oceans get precipitated. E.g. limestone, - Dolostone/Dolomite, Rock gypsum and rock salt 3. Organic Sediments and organic Sedimentary rocks Organic sediments are derived from the biological activities of various organisms, living in water bodies, which consume the weathered products in solution and sediments. The remains of dead organisms also keep on accumulating and consolidating, resulting in the formation of organic rocks e.g. coal, coprolites and guano e.g. organic lime stone. Size of Clastic Sediments Name of the particle Size or Diameter in mm Boulders 300 and above Cobbles 80 to 300 Pebbles or coarse gravel 20 to 80 Gravels or Granules 4.75 to 20 Sand (coarse and fine) 0.075 to 4.75 Silt 0.002 to 0.075 Clay <0.002 Sand stones
  59. 59. 59 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) Sandstones are clastic sedimentary rocks, formed by Lithification of sand beds of size 2mm to 0.1mm. Quartz is the chief mineral constituent. Texture: Sand stones may be of coarse and fine grained types. Types: are based on the type of cementary materials e.g. Siliceons sandstones; Calcareous Sandstones; Argillaceous Sandstones; Ferruginous Sandstones. Occurrence: They occur in thick or thin beds and sometimes as lenticular bodies within the beds of other rocks. Uses: As building stones; those with high silica and low iron are used in glass manufacture; crushed sandstones of many types are used for road construction and as rail-road ballast. Shales These are clastic sedimentary rocks formed by clay particles of less than 0.01mm in size. Depending on the clay minerals and impurities present in the rock, shales are of colours like grey, red, purple, green black etc. They are soft and brittle rocks, which crumble easily under the hammer. Types: Depending upon their composition, include: calcareous shales; siliceous or sandy shales; carbonaceous or bituminous shales; Alum shales; and oil shales. Occurrence: They occur as thin and thick beds and sometimes as small bands and irregular inclusions within other sedimentary rock formations. Uses: Because of their thin-bedded structures, sometimes cause trouble in tunneling, as the material may dislodge quite easily. They may also give trouble in dam foundations. Shales are also not as hard as sandstones and if unsupported, they may yield to the pressure of the overlying rocks. They are of no value as building stones. But, they are used in the manufacture of clay products, such as, bricks, tiles, sewer pipes; and Portland cement. Conglomerates These are clastic sedimentary rocks, with the constituent fragments of more than 2mm in size they consist of rounded pebbles, gravels, boulders e.t.c cemented together. Types: Volcanic conglomerates; Basal Volcanic conglomerates; Glacial conglomerates; Gravel conglomerates (fragment size = 4.75 to 20mm); Pebble conglomerates (fragment
  60. 60. 60 KYU, DCBE, BENG. CBE 2 & BEEEM 2, Engineering Geology Notes, for Sem.2, 2010/2011. ©Luwalaga John Groover (Mob: 0772450847; E-mail: Godblessugandanow@gmail.com) size = 20 to 80mm); cobble conglomerates (size = 80 to 300mm) and Boulder conglomerates (size>300mm). Uses: Because of their coarseness, are of little values as building stones. The harder and denser types may be used as milestone (landmark, sign post, target); also crushed stones for roads, making concretes, as rail-road ballast. Lime stone These are sedimentary rocks formed by chemical as well as organic processes. Type: chalk, argillaceous limestone, Shelley limestone, Kankar limestone, Calc-Tuffa, lithographic limestone, siliceous limestone. Uses: Used as crushed stones for road making, for concrete aggregates, used as internal and external building stones- chief ingredient in the manufacture of cement, glass manufacture, sugar refining, used in the manufacture of Rock wool/Mineral wool (insulation material: a lightweight fibrous material made from slag or glass. Use: insulation, packing material, filters); etc. Coal This is a combustible organic rock composed primarily of carbon, hydrogen, and oxygen. Coal is burned to produce energy and is used to manufacture steel. It is also an important source of chemicals used to make medicine, fertilizers, pesticides, and other products. 4.3.3 Metamorphic Rocks Metamorphic rocks (from the Greek word “Meta”, meaning between, also denoting change and “Morphe” means form or shape) are rocks changed in same way from either an original igneous or sedimentary form. The new rocks which are formed from the alteration of the pre-existing rocks of any type, by the process of metamorphism, are called metamorphic rocks. Metamorphism is defined as a process or phenomenon by which the existing rocks are modified texturally, structurally and mineralogically under the influence of factors, such as, heat, pressure and hot chemically active fluids, such as water. The Igneous and sedimentary rocks, when subjected to metamorphism, undergo changes that are physical, chemical or both. Physical changes are reflected as changes produced

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