I had created this presentation for myself about the Geologic timescale and Natural History of the Earth in terms of Galactic Years

1. Geologic Timescale and
Natural History of the Earth
Jahid Masud Akon

2. Units in geochronology and stratigraphy
Units in geochronology and stratigraphy
Segments of
rock (strata) Periods of
in time in
chronostratig geochron
raphy ology Notes
Eonothem Eon 4 total, half a billion years or more
Erathem Era 12 total, several hundred million years
System Period
Series Epoch tens of millions of years
Stage Age millions of years
smaller than an age/stage, not used by the ICS
Chronozone Chron timescale
Page  2

3. Eons
Precambrian Supereon
Present
time
18.28 GY
15.2 10 2.2
=4570 Ma
Hadean Archean Proterozoic Phane
770 Ma 1300 Ma 1958 Ma
rozoic
Formation of the Earth and later, Moon (Cryptic Era)
542 Ma
First lifeform and self replicating RNA appears (16 GY, Basin Groups Era)
First simple single-celled life (Prokaryote, Eoarchean Era)
First complex single-celled life
(Eukaryote, Statherian Period)
First multi-cellular animal (Metazoan, Ediacaran Period)
1 GY = 250 Ma Cambrian Explosion (Cambrian Period)
(GY = Galactic Year, the time the Solar System
takes to go round the centre of the Galaxy once;
Ma = Millions of years (ago), Megaanum)
Page  3

4. Hadean & Archean Eon to Eras
18.28 GY
15.2 10 2.2
Phanerozoic
Hadean Archean Proterozoic
50 Ma First known oxygen-producing
bacteria; Oldest cratons on earth
Formation of Moon from Lower
giant impact (4533Ma) 70 Ma Imbrian
Nectarian
Proterozoic
Eon
230 Ma 200 Ma 400 Ma 400 Ma 300 Ma
420 Ma
Basin Eoarchean Paleo Meso Neo
Cryptic
Groups archean archean archean
Solar
Nebula 15.4
16.6 15.68 15.2
14.4 12.8 11.2 10 Paleoproterozoic
18.28 GY
Era
=4570 Ma
First lifeform and
self-replicating First simple single-celled life (bacteria
RNA appears & archaea); Oldest probable microfossils
(4000Ma)
Formation First stromatolites (probably colonial
End of the Late Heavy Bombardment of
of the Earth cyanobacteria); Oldest macrofossils
the inner solar system.
Oldest known mineral, Zircon
Page  4 (4406 Ma)

5. Proterozoic Eon to Eras & Periods
18.28 GY
15.2 10 2.2
Phanerozoic
Hadean Archean Proterozoic
Archean
Phanerozoic
Eon 250 Ma
Rhyacian
200 Ma
Statherian
200 Ma 150 Ma 88 Ma
Eon
Ectasian Tonian Ediacaran
200 Ma 250 Ma 200 Ma 200 Ma 220 Ma
Siderian Orosirian Calymmian Stenian Cryogenian
9.2 8.2 7.2 5.6 4.8 3.4 2.52
Neoarchean 4
Cambrian
2.2
Era 10 GY Paleoproterozoic 6.4
Mesoproterozoic Neoproterozoic Period
900 Ma 600 Ma 458 Ma
Snowball Earth
Period
First complex single-celled life
Green algae colonies in sea
Era (Eukrayote)
First multi-cellular animal (Metazoan);
First sponges, trilobitomorphs
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6. Phanerozoic Eon to Eras
18.28 GY
15.2 10 2.2
Hadean Archean Proterozoic Phanero
zoic
Precambrian
Supereon &
Proterozoic
Eon
Ediacaran
Period 2.2
Paleozoic 1 Mesozoic 0.26
Cenozoic
291 Ma 186 Ma 65 Ma
(= 65 Ma)
Page  6

7. Paleozoic Era to Periods
Proterozoic
Eon 2.2 GY
Paleozoic 1 Mesozoic 0.26
Cenozoic
(= 65 Ma)
First clubmosses, ferns,
seed-bearing plants, trees,
Cambrian Explosion; insects, aquatic amphibians
Precambrian First chordates appear;
Atmospheric CO2 content
Supereon & 20-35 times present day levels First reptiles, coal forests;
Proterozoic Highest-ever atmospheric O2 level Mesozoic
Eon letting arthropods to flourish
Era
54 Ma 44 Ma 28 Ma 56 Ma 60 Ma 49 Ma
Cambrian Ordovician Silurian Devonian Carboniferous Permian
Ediacaran Period
Triassic
542 Ma 444 416 251 Period
488 360 300
(= 2.2 GY) (= 1 GY)
First green plants Pangea formed; First true seed-plants
& fungi on land (conifers) & mosses replace coal-age flora
First vascular plants, jawed fishes;
First millipedes & arthropleurids on land;
Permian-Triassic Mass Extinction
Sea-scorpions reach large size
(95% life goes extinct)
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8. Mesozoic Era to Periods
Proterozoic
Eon 2.2 GY Paleozoic 1 Mesozoic 0.26
Cenozoic
(= 65 Ma)
First birds & lizards; ichthyosaurs, plesiosaurs,
gymnosperms (conifers, cycads) diverse; K-T Mass Extinction
Breakup of Pangaea into Gondwana and Laurasia Most large animals (dinosaurs) go extinct
Paleozoic
Era Cenozoic
Era
51 Ma 55 Ma 80 Ma
Triassic Jurassic Cretaceous
Permian Period
Paleogene
251 Ma 200 145 Period
(= 1 GY) 65
(= 0.26 GY)
Archosaurs dominate as dinosaurs, Flowering plants, new insect types,
ichthyosaurs, nothosaurs & pterosaurs; new dinosaur types, new eusuchians, modern sharks,
First mammals, crocodilians, teleosts appears monotremes, marsupials, placental mammals appear;
Primitive birds gradually replace pterosaurs
Page  8

9. Cenozoic Era to Periods and Epochs
Proterozoic
Eon 2.2 GY Paleozoic 1 Mesozoic 0.26
Cenozoic
(= 65 Ma)
First large mammals, Ice Age recedes;
modern plants appear; Rise of human civilization
Evolution of anatomically modern humans;
Indian subcontinent collides with Asia 55Ma Dawn of human stone-age cultures
Mesozoic 2.489 Ma
Era Grass appears; atmospheric Pleistocene
2.8 Ma
CO2 decays
Pliocene
Holocene
9.2 Ma 21.8 Ma 11 Ma 17.7 Ma 0.0114 Ma
Paleocene Eocene Oligocene Miocene
Permian Period
65 Ma
(= 0.26 GY) 55.8
34 2.5
5.3 0.0114
42 Ma 23 23 Ma (=11.4 ka)
Paleogene Neogene
Epoch
Period First apes appear
Major evolution & dispersal
of modern types of Austrapithecines appear;
Page  9 mammals & flowering plants Homo habilis appears;
Present Ice Age begins;

10. The End
Page  10