Exam 2 Review Answers

Topics: Plate tectonics, Mountains and geologic structures, Earthquakes, Volcanoes and lava features; Weathering; Soils; Erosion and Mass wasting.

Note: This is NOT intended to provide a comprehensive review. The questions below are examples of the type of questions that you should expect on the exam.

Practice questions: True or false?

__F__ (1) Continental crust is composed primarily of basalt.

__T__ (2) As new sea floor crust cools, it acquires the orientation of the Earth's magnetic field.

__T__ (3) Where two tectonic plates move past one another, rock near the plate boundary often stretches and stores elastic energy.

__F__ (4) Basaltic magma has short silica chains and is therefore viscous and does not flow easily.

__T__ (5) Shallow earthquakes and high heat flow occur at the mid-ocean ridge.

__T__ (6) During an earthquake, surface waves radiate away from the epicenter along the surface of the earth like the waves that form when you throw a rock into a calm lake.

__T__ (7) A dike forms when magma oozes into a crack running across the layers of surrounding rock.

__T__ (8) A thick cover of vegetation decreases soil erosion.

Multiple choice.

__D__ (9) The lithosphere is

(a) hot and plastic
(b) mostly liquid magma
(c) composed of sedimentary rocks
(d) cool and brittle

__B__ (10) The edges of two plates may remain stationary while the interiors of the plates move because

(a) rock is brittle
(b) rock is elastic
(c) the plates are fused solidly
(d) rock is non elastic

__D__ (11) Waves that travel through rock are called

(a) cosmic waves
(b) earth waves
(c) focal waves
(d) seismic waves

__D__ (12) The damage caused by an earthquake depends on

(a) Richter magnitude
(b) proximity to population centers
(c) quality of building construction in the affected area
(d) all of the above
(e) none of the above

__A__ (13) Pillow lava

(a) erupts under water
(b) forms from spheroidal weathering
(c) usually has a granitic composition
(d) all of the above
(e) none of the above

__C__ (14) If basaltic magma is too viscous to form a lava plateau, but still quite fluid, it heaps up slightly to form

(a) flood basalts
(b) pillow lavas
(c) shield volcanoes
(d) cinder cones

__A__ (15) The Andes mountains were formed by

(a) subduction
(b) continent-continent collision
(c) a shield volcano
(d) a hot spot
(e) a transform plate boundary

__B__ (16) The Appalachian mountains were formed by 3 distinct orogenies that span the period from

(a) 6 billion to 4 billion years ago
(b) 600 to 250 million years ago
(c) 60 to 25 million years ago
(d) 600,000 to 250,000 years ago

Short answer.

(17) List (in order) the rock types you would be likely to find moving from the continental coastal plain across the continental shelf to the surface of the deep ocean floor.

sandstone, siltstone, shale, limestone

(18) How do the seismic waves generated by an earthquake measuring 8.6 on the Richter scale and recorded on a seismograph compare to those generated by a quake measuring 5.6?

1000 times