landforms and landscapes of mountain glaciers. objectives examine the current distribution of...

Landforms and Landscapes of Mountain Glaciers

Objectives

• Examine the current distribution of mountain glaciers and to comment on the Late Cenozoic extent of these glaciers

• Describe the characteristic landforms produced by mountain glacier erosion

• Discuss the landforms produced by glacial deposition in mountain landscapes

Global Distribution of Mountain Glaciers • North America– Major clusters lie in the

Arctic islands of Canada, southeastern Alaska, Canada’s Yukon & Coast Mountains of British Columbia, and Canadian Rocky Mountains

• South America– Just south of 45°S in

southern Andes of Chile

Global Distribution of Mountain Glaciers

• Africa– Only two exist• Mt. Kilimanjaro• Mt. Kenya

• New Zealand– Occur in Southern Alps– Several glaciers still exist

around Mt. Cook

Global Distribution of Mountain Glaciers

• European Alps– Most famous– Extends from

southeastern France to Swiss-Italian border

– Mont Blanc is highest sitting at 4807 m (15,771 ft)

Global Distribution of Mountain Glaciers

• South-central Asian Alps– Largest mountain system– Extends from

Afghanistan to southwestern China

– World’s highest mountain – Mt. Everest 8850 m (29,035 ft)

Erosional Landforms of Mountain Glaciers

• Glacial Troughs – widening of valley bottom producing a U-shaped valley

Erosional Landforms of Mountain Glaciers• Truncated Spurs– ridge of land is cut off

producing a blunt-ended ridge; caused by erosion of moving glaciers

• Hanging Valley– Tributary valley sits

higher than main valley floor

– Marked by scenic waterfall

Formation of High-Mountain Landforms

• Accumulation of snow• Downslope movement

of ice under gravity• Glacial erosion occurs• Transforms source

areas of glaciers

High-Mountain Landforms

• Cirques – amphitheater-like landform; bowl-shaped, steep-sided depression in bedrock

High-Mountain Landforms• Horn– Multiple cirque develop around mountain peak– Steep-sided, sharp-edged peak remains

High-Mountain Landforms• Aretes– Razor-sharp, jagged

ridges rising above glacial troughs

– Forms at the interaction of two large cirques

• Rock Steps– Step-like profile

formed by differential resistance

High-Mountain LandformsGlacial Lakes are depressions formed by glacial erosion and filled by water during interglacial period•Tarns– Lakes dammed up behind edge of cirque

High-Mountain Landforms

• Fjords– Narrow, steep-sided, elongated ocean inlet– Area where glacial troughs inundated by seawater

Depositional Landforms of Mountain Glaciers

• Rock Flour– Grounded up, fine-grained sediment

• Lateral Moraines– Ridge of debris located along both sides of a glacier

• Medial Moraines– Linear debris marked the boundary between two glaciers

Depositional Landforms of Mountain Glaciers

Postglacial Landscape Change

• Glacial areas are not stable• Modifications are quite rapid• Produce scenic areas