Exam 2 Ch 5-8 test prep

Question 1

What type of magma erupts from Hawaiian volcanoes?

Answer 1

basaltic

Question 2

_____ magma is the most viscous (sticky); therefore, it produces ________ eruptions.
A) Andesitic; fluid
B) Basaltic; violent
C) Rhyolitic; violent

Answer 2

C) Rhyolitic; violent

Question 3

Which type of magma has the highest silica content: basaltic, andesitic, rhyolitic?

Answer 3

rhyolitic

Question 4

Name three geologic events associated with the eruption of Mount St. Helens.

Answer 4

Earthquake triggered a landslide; pyroclastic flow; lahar

Question 5

How does a caldera form?

Answer 5

Collapse of the volcano into the magma chamber after eruption

Question 6

It would be unwise to build your house along the _______ of a stream because erosion is the dominant force there?

Answer 6

Cut bank

Question 7

What does the dissolved load in streams consist of?

Answer 7

Dissolved ions (minerals)

Question 8

What happens to the discharge of the Colorado as it reaches its mouth (Gulf of California)? Why?

Answer 8

Discharge decreases to near zero (no flow) because of all the big cities that use Colorado River water (Las Vegas, L.A.)

Question 9

How does urbanization affect lag time?

Answer 9

Shortens the lag time (time between rainfall and flooding)

Question 10

A river system consists of three zones. Which of the following is characteristic of Zone 3?
A) Broad floodplain
B) Flash flooding
C) Formation of a delta
D) Erosion

Answer 10

C) Formation of a delta

Question 11

What two horizons make up the topsoil?

Answer 11

O & A (What does the O stand for?)

Question 12

It takes 500 years for 2 \_\_\_\_\_ of soil to form. From this we see that time greatly affects soil development.
A) meters
B) inches
C) feet
D) kilometers

Answer 12

B) inches

Question 13

Name two features associated with karst topography

Answer 13

Sink holes, caves, disappearing streams

Question 14

How have humans contributed to subsidence along the Mississippi Delta? List three ways

Answer 14

Restricting sedimentation by building dams and levees
Withdrawal of oil and groundwater
Canal building which allows salt water to invade and kill plants

Question 15

A soil _________ is an arrangement of soils from youngest to oldest based on their relative development.

Answer 15

chronosequence

Question 16

What happens when driving forces overcome resisting forces?

Answer 16

Slope failure! (a landslide)

Question 17

Wildfires are a frequent occurrence in California. Which mass wasting process typically follows the first rainstorm after a fire? (Hint: they consist of soil, regolith and a large amount of water)

Answer 17

Debris flow

Question 18

What causes soil to creep?

Answer 18

Expansion and contraction of the ground due to freeze/thaw cycles, causing soil particles to move downslope

Question 19

Rocks do not weather uniformly which causes overhanging ledges of resistant rocks over eroded ones. What type of mass wasting event would this likely cause?

Answer 19

Rock fall

Question 20

List some factors responsible for causing the large Gros Ventre landslide outside of Jackson, WY.

Answer 20

Rain and snowmelt saturated a sandstone layer that rested on top of an impermeable (and slick when wet) layer of shale (clay)

Question 21

When did Lake Bonneville reach its highest elevation?

Answer 21

17,000 years ago

Question 22

What caused the lake level to drop precipitously over the course of a few weeks/months) from its highest level?

Answer 22

A catastrophic flood at Red Rock Pass in southern Idaho

Question 23

What type of volcano typically occurs in clusters and has a life span of several years

Answer 23

Cinder cone

Question 24

What type of mass wasting event occurs as blocks of rock slide down a slope?

Answer 24

Rock slide

Question 25

What forms when a river abandons its meander?

Answer 25

Oxbow lake