Geology Quiz 4-Glaciers

Thick masses of recrystallized ice

glaciers

Glaciers flow via...

gravity

Glaciers cover ___% of Earth's surface

10%

Glaciers cover ___% of Earth's surface during Ice Ages

30%

Glacier formation

Snowfall accumulates and compresses into ice, survives the following summer

Glaciers that flow from high to low elevations

Mountain glaciers

Glacier that fills mountain top bowls

Cirque glaciers

Glaciers that flow down valleys like rivers

Valley glaciers

Glaciers that covers peaks and ridges

Mountain ice caps

Glaciers that spread out at end of valley

Piedmont glaciers

Glaciers that are vast ice sheets covering large land areas

Continental glaciers

Continental glacier movement

Ice flows outwards from thickest part of sheet

Movement where significant meltwater decreases friction as glacier slides

Basal sliding

Basal sliding depth

on surface

Movement where grains of ice change shape

Plastic deformation

Plastic deformation depth

below 60m

Forms at the surface of plastic deformation

crevasses

Area of net snow addition

Zone of accumulation

Zone of accumulation

Temps prevent melting, accumulates

Area of net ice lost

Zone of ablation

Glacier toe is stationary

accumulation=ablation

Glacier toe retreats upslope

accumulation < ablation

Glacier toe advances downslope

accumulation > ablation

Zone of accumulation and zone of ablation meets at the...

equilibrium line

A sandpaper effect/pulverization of substrate

glacial abrasion

Glacial erosion that run parallel to direction of ice movement

striations

Ice freezes around bedrock fragments and moves chunks

Glacial plucking

Distinctive asymmetric hill as a result of plucking

roche moutonee

Glaciers acting as large-scale conveyor belts

glacial deposition

Sediments transported by glaciers and deposited in ice or meltwater

Glacial drifts

Sorted, layered sediments deposited by meltwater

Stratified drift

Unsorted sediments deposited by ice

Unstratified drift

Sediments dropped by glacial ice

Glacial till

Glacial till grain size

all grain sizes

Ridges of unsorted till deposited at toe of glacier

End moraines

Ridge of unsorted till deposited at the maximum extent of glacier

Terminal moraines

Ridges of unsorted till deposited at temporary halts

Recessional moraines

Flat blankets of unsorted till deposited beneath glacier

Ground moraine

Body forms from stranded ice blocks from ground moraines

Kettle lakes

Long, teardrop-shaped hills formed beneath glaciers

Drumlins

Drumlin movement direction

parallel to ice flow direction

Long, curvy ridges of sand and gravel deposited beneath glaciers

Eskers

Eskers form as...

meltwater channels within/below ice- deposited when ice melts

Glaciers indicated with fossil tills and layer bedrock

Ancient Glaciations

Tills at the equator suggest an ice-covered world (snowball Earth) during...

Late Proterozoic era

Causes of glaciation

1) plate tectonics

2) atmospheric chemistry

How do plate tectonics influence glaciation

controls factors

Glaciation factors controlled by plate tectonics

-Volcanoes

-Continental rise

-Sea level flux

-Oceanic currents

How does atmospheric chemistry affect glaciation?

Changes in greenhouse gas concentrations (CO2 and CH4)