material that is deposited directly by the ice

unsorted and unsatrtratified

(unlayered/ unbedded)

Sediments laid down by glacial meltwater streams

sorted and stratified

(layered/ bedded)

Moraines

Layers or ridges of till

Lateral moraine

Medial moraine- within the glacier

End morain- terminal or recessional (where the ice stops)

End moraine- terminal or recessional

Ground moraines

Smooth, elongated, parallel hills

Steep side faces the direction from which the ice advanced

ocurr in clusters called drumlin swarms or drumlin fields

Formation not fully understood

Hypothesis- deformation of prexisting landform by advancing glacier

Deposited by meltwater flowing over, within, anad at the base of motionless ice

Kettles

Kames

Eskers

Growth of high latitude/ polar ice masses

Relatively low atmospheric green house gas concentrations

Low sea levels

Shift of precipitation to higher latitudes

Small or poorly connected oceans

Start gradually/ end abruptly

Began 2.6 million years ago

Ended 10,000 years ago

4 stages

Up to 20 major stages

Ice covered 30% of Earth's land area

Nebraskan (oldest)

Kansan

Illinoian

Wisconsian (youngest)

Controversial hypothesis- Complete glaciation of earth's surface

Problems- very little surface of that age is available to search for evidence

Evidence itself is disputed

Continental land masses are in equalatorial regions

No known mechanisms to cool earth that much