Glacial Basics
What is the name for the tightly packed ice grains that form after snow survives a summer?
Firn
What is the zone called where snow and ice build up on a glacier?
Zone of accumulation.
What is unsorted sediment deposited directly by glacial ice called?
Till
Many of the world’s largest deserts are located near which latitude?
30* north and south
What is the steep side of a dune called where sand avalanches down?
Deflation
Which type of glacier is found on high mountains at all latitudes?
Alpine
What do you call a deep crack that forms in the brittle upper layer of a glacier?
Crevasse
What is a long, sinuous ridge formed by sediment deposited by a subglacial stream?
Esker
What is the name for the dry side of a mountain that receives little precipitation?
Leeward
What is the steep side of a dune called where sand avalanches down?
Slip face
What must happen (relationship between snowfall and melting) for a glacier to form?
More snow must fall in the winter than melts in the summer.
Give the two main ways glaciers move (one involves sliding over bedrock; the other involves internal deformation).
Basal slip and plastic flow
What term describes large rocks transported by glaciers that rest on a different bedrock type?
Erratic
What is the process called when moist air rises on the windward side of a mountain, drops moisture, and creates an arid area on the other side?
Rain-shadow effect
What is the name of the crescent-shaped dune with tips pointing downwind?
Barchan dune
Name the second-largest alpine glacier in the Alps referenced in the text.
Gorner Glacier
Why do crevasses form only in the upper ~40 meters of a glacier?
The upper ~40 m is brittle and fractures; deeper ice deforms plastically under pressure, so it bends instead of cracking.
Which moraine marks the farthest advance of a glacier?
Terminal moraine
Explain, with scientific reasoning, why sinking air near 30° N and S produces dry surface conditions.
Sinking air warms, increasing its capacity to hold water vapor. (It becomes warmer)
Define loess and give one impact that loess deposits can have on agriculture or human structures.
Loess is windblown silt; it forms fertile soils beneficial to agriculture but can create unstable cliffs prone to collapse and erosion.
Explain why some mountains in warmer regions can have larger glaciers than colder regions elsewhere.
Warmer mountains with much higher snowfall can accumulate more snow than colder areas with low precipitation; accumulation vs. ablation controls the glacier size.
Describe what will likely happen to an alpine glacier's terminus and thickness if the climate warms and snowfall decreases over several years.
The terminus will retreat upslope, and the glacier will thin.
Compare moraine formation and esker formation (one-sentence contrast).
Moraines are deposited directly by ice as unsorted till forming ridges; eskeras are sinuous ridges of sorted sediment deposited by subglacial meltwater streams.
Using climate graph criteria, list three features you would look for to identify a desert biome and name two types of vegetation you would expect.
Look for consistently low precipitation, low monthly/annual rainfall totals, and often moderate-to-high temperatures; expect sparse vegetation such as cacti and drought-resistant shrubs.
Describe how a sand dune migrates over time (mention windward side, slip face, and overall movement).
Wind erodes sand from the windward side (saltation and deflation), transports it over the crest, and deposits it on the slip face; repeated cycles move the dune downwind.