2. Original Horizontality
The principle of original horizontality states
that most sedimentary layers of rock are
deposited in a horizontal position.
http://www.classzone.com/books/earth_science/te
If rock layers are not horizontal, something
must have disturbed them after they formed.
3. Geologic Column
An ideal sequence of rock layers that contains
all the known fossils and rock formations on
Earth, arranged from oldest to youngest.
Geologist use the geologic column to:
interpret rock sequences
Identify the layers in puzzling rock sequences
The deeper and older, the simpler organisms are
4. How Rock Layers Become Disturbed:
Fault: a break in the
Earth’s crust along which
blocks of the crust slide
relative to one another
Intrusion: molten rock
from the Earth’s interior
that squeezes into existing
rock and cools
Folding: occurs when rock
layers bend and buckle
from Earth’s internal
forces.
Tilting: Occurs when
internal forces in the Earth
slant rock layers.
5. Unconformity
A surface that represents a missing part of the
geologic column.
Also represent missing time - time that was
not recorded in layers of rock.
Was it ever there? Was it removed?
6. Unconformity
A surface that represents a missing part of the
geologic column.
Also represent missing time - time that was
not recorded in layers of rock.
Was it ever there? Was it removed?
