GLACIERS Formation Snow accumulation More winter snowfall than

GLACIERS

Formation Snow accumulation More winter snowfall than summer melt Glacier formation is similar to sedimentary rock formation

Types of Glaciers Valley glaciers or alpine glaciation Ice sheets or continental glaciation

Glaciers of the world 85% of glacier ice in Antarctica 10% of glacier ice in Greenland Alpine glaciers comprise only 5% of world’s glacier ice

Alpine Glaciers Form in valleys Gravity causes glacier movement Glaciers flow from higher to lower elevation

Alpine Glacier Flow Velocity Overall downward flow velocity ranges from a few millimeters to 15 meters per day Glaciers in warmer climate flow more quickly Central part moves faster than sides Surface moves faster than base Glacier movement Basal sliding Plastic flow Brittle/Rigid Zone

Continental Glaciers Cover a large part of a continent Gravity causes glacier movement Glaciers flow downward and outward from a central high point Plastic flow more common than basal sliding

Arctic Sea Ice Fresh water, like glaciers, but do not flow like glaciers

Glacial Erosion And resulting landscapes

Erosion Glacier movement erodes the bedrock underneath the glacier and can drastically change the landscape Plucking Abrasion Polishing Striations

Erratics & Striations

Alpine landscape features

Continental landscape features All the sediment that a glacier picks up is deposited as unsorted and unlayered rock debris called “till” Most features are created during glacial retreat

Ice Ages Effects on North America

Glacial Ages A period of long-term reduction in Earth’s temperature, resulting in the presence of continental and polar ice sheets and alpine glaciers Glacial periods Interglacials The last glacial period ended 10, 000 years ago

Glacial Extent of Last Glacial Period

Laurentide Ice Sheet Stevens Point is located right beyond the recessional moraine—in outwash plain

Glacial Erosion in Wisconsin

Topographic Maps Whitewater Wisconsin Map Activity

Topographic maps