Glaciers & Ice
What two conditions are required for a glacier to form?
Cold enough climate for snow to persist + more snow accumulation than melting.
How can you tell if a valley was carved by a glacier rather than a river?
Glacial valleys = U-shaped; river valleys = V-shaped.
How does increasing vegetation affect slope stability?
It increases stability.
What defines a desert?
Low precipitation, hot temperature.
How long is the sunspot cycle?
~11 years.
Describe how snow transforms into glacial ice
Snow compacts → turns into firn → pressure causes recrystallization → glacial ice forms.
What is a natural levee and how does it help prevent flooding?
Raised banks of deposited sediment that keep water within the channel.
Which slope orientation is least stable: layers dipping toward the slope or dipping into the slope?
Layers dipping toward the slope.
Name one geographic factor that can cause deserts to form.
Subtropical highs, rain shadows, continental interiors, cold ocean currents (any one).
What are the three Milankovitch cycles?
Eccentricity (~100,000 yrs), obliquity (~41,000 yrs), precession (~23,000 yrs).
What is the main difference between alpine and continental glaciers?
Alpine glaciers form in mountains; continental glaciers cover large landmasses.
What are the requirements for a braided stream?
High sediment load, highly variable discharge, and steep gradient.
Name two ways humans decrease slope stability.
Over-steepening slopes; removing vegetation; adding weight (any two).
Which has high porosity: well-sorted sand or poorly cemented gravel?
Both can be high, but well-sorted sand especially.
If Earth’s albedo increases, what happens to climate?
Earth cools because more sunlight is reflected.
If temperature increases and snowfall decreases, will a glacier advance or retreat?
It will retreat.
What process happens at a cut bank and at a point bar?
Cut bank = erosion; Point bar = deposition.
Name two common triggers of slope failure.
Heavy rainfall, earthquakes, volcanic activity, rapid snowmelt (any two).
What is the difference between a confined and unconfined aquifer?
Confined aquifer is trapped between aquitards; unconfined is open to the surface.
What does a high ratio of heavy oxygen isotopes in marine sediments indicate?
A cold climate with large ice volumes.
Name the two glacier movement processes and where in the glacier they occur.
• Internal deformation (plastic flow) – deep ice
• Basal sliding – base of glacier along bedrock
Why does longshore drift occur?
Wave refraction causes waves to hit the shore at an angle, creating longshore currents.
Classify a landslide involving fast movement of water-rich mud.
A mudflow (rapid, fluid mass wasting event).
Name a negative effect of overdrafting an aquifer.
Land subsidence, saltwater intrusion, wells drying up (any one).
How does the pace of modern climate change compare to the past 800,000 years?
Much faster—warming is occurring at an unprecedented rate.