EARTHSCI 1G03 - FINAL REVIEW
● Introduction and Plate Tectonics
○ Hutton’s Revolution
■ James Hutton, Scottish physician and farmer, 1726-1797
■ Founding of modern geology
■ Siccar point
■ Sediment usually gets deposited in big, flat layer - Principle of Original
Horizontality
● But this sediment is anything but horizontal, something must
have happened to the bottom layers
■ Stuff on the bottom is older than the stuff on the top
■ Super Position - position means where it is, super means the young stuff
is on top
■ 1st thing that happened is that a rock was broken up and deposited in the
steeply Silurian greywacked (jagged almost vertical rocks)
■ Basal Conglomerate - this is where the bottom layer got eroded
■ Shallowly dipping Devonian red sandstones - the almost horizontal red
stones laying on top of the Basal Conglomerate
○ Uniformitarianism
■ Means that past geological events can be explained by forces occurring
today (contrast: catastrophism)
○ Evidence of Continental Drift
■ Alfred Wegner (1880-1930) proposed that continents ‘drifted’ and had
formed from one supercontinent called Pangea (300-200 mya) into two
smaller continents: Laurasia and Gondwanaland
■ Wegner’s Hypothesis
● Modern continents move slowly over the globe and have formed
from break-up of Pangea over the last 200 million years
● Problem: there was no known mechanism for the continents to
‘plow’ through the rigid oceanic crust
■ Paleontological (Fossil) Evidence
● Fossils found on the continents that once comprised
Gondwanaland
● Fossil evidence of the same species found in Antarctica, South
Africa, and India - species that is not meant to traverse large
bodies of water
■ Geologic Evidence
● Rock units on different continents w similar structural style (how
the rocks have been deformed, pressure, temperature, etc.) line
up into continuous chains if Pangea is reconstructed
■ Much evidence for continental drift, but we still need a mechanism to
explain how and why the continents have been moving all over the globe
● Introduction and Plate Tectonics
○ Hutton’s Revolution
■ James Hutton, Scottish physician and farmer, 1726-1797
■ Founding of modern geology
■ Siccar point
■ Sediment usually gets deposited in big, flat layer - Principle of Original
Horizontality
● But this sediment is anything but horizontal, something must
have happened to the bottom layers
■ Stuff on the bottom is older than the stuff on the top
■ Super Position - position means where it is, super means the young stuff
is on top
■ 1st thing that happened is that a rock was broken up and deposited in the
steeply Silurian greywacked (jagged almost vertical rocks)
■ Basal Conglomerate - this is where the bottom layer got eroded
■ Shallowly dipping Devonian red sandstones - the almost horizontal red
stones laying on top of the Basal Conglomerate
○ Uniformitarianism
■ Means that past geological events can be explained by forces occurring
today (contrast: catastrophism)
○ Evidence of Continental Drift
■ Alfred Wegner (1880-1930) proposed that continents ‘drifted’ and had
formed from one supercontinent called Pangea (300-200 mya) into two
smaller continents: Laurasia and Gondwanaland
■ Wegner’s Hypothesis
● Modern continents move slowly over the globe and have formed
from break-up of Pangea over the last 200 million years
● Problem: there was no known mechanism for the continents to
‘plow’ through the rigid oceanic crust
■ Paleontological (Fossil) Evidence
● Fossils found on the continents that once comprised
Gondwanaland
● Fossil evidence of the same species found in Antarctica, South
Africa, and India - species that is not meant to traverse large
bodies of water
■ Geologic Evidence
● Rock units on different continents w similar structural style (how
the rocks have been deformed, pressure, temperature, etc.) line
up into continuous chains if Pangea is reconstructed
■ Much evidence for continental drift, but we still need a mechanism to
explain how and why the continents have been moving all over the globe
