Geology Midterm Study Guide

Review for Midterm
Earth is 4.6 billion years old

What do Geologist do
Study the structure of mountain ranges
Attempt to predict geological hazard
Principle of parsimony = Occams Razor (Simpler is better)

Deep Time
The amount of time of Earth’s existence
Universe began=Big Bang Theory
Earth’s creation= Nebula hypothesis
Geological time Scale
Largest units to smallest (EEPE)
Eons
Eras
Periods
Epocs
Cambrien Explosion
Mass amount of fossils found in the Cambrien time period
Names come from location
Precambria
88.1% of the geological time scale
Geologic Range
The existence of an organism
Methods of dating rocks
Absolute Age dating (1896)
Half lives. Jangus you know this
Relative Age dating
You know this too gumbus

Plate Tectonics
Lithosphere is divided into plates
7 large plates
20 smaller plates
Rigid lithosphere
Rest on the asthenosphere (the easily deformed or partially molten part of mantle below the lithosphere
Plates move 3-5 cm/year
How do they move?
Convectional flow
Circular movement in the asthenosphere
Hot material rising cool sinking
3 Ways
Divergent
Plates move apart from one another
Convergent
Plates move toward another
Transform
Two plates slide past one another.

Evolution

Modern Organisms
Vestigial organs
“tail bone”
Organic Evolution
The study of fossils in geology
Early Interpretation of Fossils
Herodotus (450 B.C.)
Found seashells in sedimentary rocks.
Sea level must have dropped
Fossils
Forms
Rapid burial
Sediment to prevent destruction of the dead organism by scavenging or bacterial decay
Fossil Types
Freezing
Desiccation/Mummification
Preservation in tar
Preservation in peat bogs
Carbonized imprints in fine-grained sediment
Three Major rock types
Igneous
Fire rocks
Metamorphic
Change rock by heat and pressure
Sedimentary
From sediment
Three types
Clastic
Biologic
Chemical

Sedimentary:
Formed from pre-existing rocks or pieces of once-living organisms.