Exam 2 Ch 5-8 test prep Flashcards
What type of magma erupts from Hawaiian volcanoes?
basaltic
_____ magma is the most viscous (sticky); therefore, it produces ________ eruptions.
A) Andesitic; fluid
B) Basaltic; violent
C) Rhyolitic; violent
C) Rhyolitic; violent
Which type of magma has the highest silica content: basaltic, andesitic, rhyolitic?
rhyolitic
Name three geologic events associated with the eruption of Mount St. Helens.
Earthquake triggered a landslide; pyroclastic flow; lahar
How does a caldera form?
Collapse of the volcano into the magma chamber after eruption
It would be unwise to build your house along the _______ of a stream because erosion is the dominant force there?
Cut bank
What does the dissolved load in streams consist of?
Dissolved ions (minerals)
What happens to the discharge of the Colorado as it reaches its mouth (Gulf of California)? Why?
Discharge decreases to near zero (no flow) because of all the big cities that use Colorado River water (Las Vegas, L.A.)
How does urbanization affect lag time?
Shortens the lag time (time between rainfall and flooding)
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
C) Formation of a delta
What two horizons make up the topsoil?
O & A (What does the O stand for?)
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
B) inches
Name two features associated with karst topography
Sink holes, caves, disappearing streams
How have humans contributed to subsidence along the Mississippi Delta? List three ways
Restricting sedimentation by building dams and levees
Withdrawal of oil and groundwater
Canal building which allows salt water to invade and kill plants
A soil _________ is an arrangement of soils from youngest to oldest based on their relative development.
chronosequence
What happens when driving forces overcome resisting forces?
Slope failure! (a landslide)
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)
Debris flow
What causes soil to creep?
Expansion and contraction of the ground due to freeze/thaw cycles, causing soil particles to move downslope
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?
Rock fall
List some factors responsible for causing the large Gros Ventre landslide outside of Jackson, WY.
Rain and snowmelt saturated a sandstone layer that rested on top of an impermeable (and slick when wet) layer of shale (clay)
When did Lake Bonneville reach its highest elevation?
17,000 years ago
What caused the lake level to drop precipitously over the course of a few weeks/months) from its highest level?
A catastrophic flood at Red Rock Pass in southern Idaho
What type of volcano typically occurs in clusters and has a life span of several years
Cinder cone
What type of mass wasting event occurs as blocks of rock slide down a slope?
Rock slide
What forms when a river abandons its meander?
Oxbow lake
