Geology Study Guide

Geol 107 Final Exam Questions

1. What is the Earth’s magnetic field and what causes it?

Earth’s magnetic field is largely a dipole, meaning that it has two poles- a north pole and a south pole.

2. What are faults and how are different types defined?

A fault is a large fracture on which sliding occurs, that slopes gently to the west. Motion along a fault doesn’t happen continuously, but rather rocks along a fault slowly bend and eventually snap. The intersection between a fault and the ground surface is the fault trace, or fault line

A) Normal faults form during stretching or extension of the crust. The hanging wall moves down

B) Reverse faults form during squeezing and shortening of the crust. The hanging wall moves up and the fault is steep.

C) Thrust faults also form during shortening of the crust, but the fault’s slope is gentle (<30 degrees)

D) On a strike-slip fault, one block slides laterally past another, so no vertical displacement takes place

E) As oceanic plates spread apart at mid oceanic ridges, they must slide past other plates, along transform faults

3. What is the lithosphere and asthenosphere? (defined by strength)

The lithosphere is a zone of strength, where if you apply enough stress, it will break causing an earthquake. The lithosphere is 0-100 km thick between oceans, and 100-150 km thick between continents. The lithosphere consists of the crust plus the uppermost part of the mantle.

The asthenosphere is a zone of weakness, where if you apply enough stress, the asthenosphere will flow. It is 200 km thick and occurs beneath the lithosphere. Lithospheric plates move on top of asthenosphere. The asthenosphere is the portion of the mantle in which rock can flow.

4. What are the internal chemical layers in the Earth and how are they defined?

Crust- there are two basic types of crust. The oceanic crust is thinner and consists of basalt and gabbro. Continental crust varies in thickness and rock type. Oceanic...