DYNAMIC EARTH: GLACIERS
How did "Snowball Earth" affect plate tectonics?
distribution of continents toward hihg latitudes
In glacial budgets, ice always flows _____, even during _____.
downhill, retreat
What are long, aligned hills of till called and what is their form?
drumlins, asymmetric
What are long, sinuous ridges of sand and gravel called?
eskers
What is the intersection of a tributary glacier with a main glacier called?
hanging valley
The zone of accumulation is the area of what?
net snow addition
What are the 2 zones of glacial budgets?
zone of accumulation, zone of ablation
Calving is when an iceberg is _____ _____ the water. An example?
4/5 beneath, Titanic
In equatorial regions, glaciers form above what?
5km elevation
Where do 2 major ice sheets remain on Earth?
Antarctica, Greenland
A low amount of what 2 greenhouse gases causes the Earth to be cooler?
CO2, CH4
What are U-shaped glacial troughs flooded by the sea called?
Fjords
What are hills of bedrock abraded smooth on the upstream side by steep and rough on downstream side due to ice plucking called?
Roche Mountonee
What is it called when ice slips over water flowing along the base of the glacier?
basal sliding
During glacial plucking, rock fragments are dragged along the _____ of the _____. Water seeps into cracks, freezes, and mechanically breaks up the _____.
base, glacier, bedrock
How do greenhouse gases trap heat?
by absorbing solar energy
"Snowball Earth" affected atmospheric chemistry by changing what 2 greenhouse gas concentrations?
carbon dioxide (CO2), methane (CH4)
What are bowl-shaped basins high on a mountain called?
cirques
What are 2 possible conditions for glacier formation?
cold climate (polar latitudes or high elevation), wet climate
What are boulders dropped by glacial ice called and what are they different from?
erratics, underlying bedrock
When water is stored on land during an ice age, sea level _____. When deglaciation returns water to the oceans, sea level _____.
falls, rises
During glacial abrasion, pulverizations produces what and polishes what?
fine-grained "rock flour", bedrock
Varves have the finest silt and clay from what? And they have coarser silt and sand from what?
frozen winter months, summer meltwater
What is it called when there is a "sandpaper" effect on substrate?
glacial abrasion
What is sediment transported in meltwater called?
glacial outwash
During what process are the broken bedrock fragments plucked out by glacier?
glacial plucking
What is it called when rock is surrounded by frozen water and carried off?
glacial plucking
Valley glaciers flow from _____ to _____ in mountain settings.
high, low
What is a pointed mountain peak called?
horn
What are 3 types of ice rock?
igneous, metamorphic, sedimentary
What are depression formed from stranded ice blocks called?
kettle lakes
An arête are a "_____-_____" ridge with two glaciers _____ _____ one another.
knife-edge, eroding towards
What are 3 characteristics of thick masses of recrystallized ice?
last all year long, flow via gravity, 2 forms of glaciers
For a glacier to sustain elevation, it must be controlled by what?
latitude
What is wind-transported rock flour called? Ex. in LA?
loess, Tunica Hills
The zone of ablation is the area of what? And through what 3 things?
net ice loss, melting & evaporation & calving
What is year-round frozen soil called? And what do its free-thaw cycles generate?
permafrost, unusual patterned ground
Long-term causes of "Snowball Earth"? affected what 2 major things?
plate tectonics, atmospheric chemistry
Glacial tills are _____ sorted, _____ sediment dropped by glacial ice that consists of _____ grain sizes.
poorly, unstratified, all
Ice ages cause sea level to do what?
rise and fall
In polar regions, glaciers form at _____ _____.
sea level
Ice shelfs are thin ice sheets floating where and are attached to what?
sea, main glacier
What are 2 characteristics of glacial outwash sizes? Grains?
sizes - graded, stratified grains - abraded, rounded
In order for a glacier to form in a wet climate, what needs to occur?
snow must be abundant; more snow must fall than melts
What is the gouging of bedrock by large rocks that show direction of ice movement called?
striations
In what 2 ways were weather patterns different during ice ages?
the American SW was much wetter, all climate changed + vegetations belts shifted southward
During basal sliding, water lubriacates what?
the base
In continental glaciers, the ice flows outward from what part of the sheet?
thickest
What are 2 forms of glaciers?
valley, continental
What is a seasonal glacial lake-bed sediment called?
varve
When did the most recent ice age end?
~11 ka
During ice ages, glacier coverage is what percentage?
~30%
"Snowball Earth", when a large % of Earth was covered in ice, occurred how many years ago and where can evidence be found?
~700 million, equatorial latitudes
