Glaciers and Glacial Mechanics

Glacier Origins and Types

Glacier Origins and Types Glacier (def): a body of moving ice that has been formed on land by compaction and recrystallization of snow.

Glacier Origins and Types Glacier (def): a body of moving ice that has been formed on land by compaction and recrystallization of snow. B. Critical Requirements

B. Critical Requirements Must be formed from the accumulation and ‘metamorphism’ of snow.

B. Critical Requirements Must be formed from the accumulation and ‘metamorphism’ of snow. 2. Ice must be moving under its own weight.

B. Critical Requirements Must be formed from the accumulation and ‘metamorphism’ of snow. Ice must be moving under its own weight. Must originate on land

B. Critical Requirements Must be formed from the accumulation and ‘metamorphism’ of snow. Ice must be moving under its own weight. Must originate on land Persist from year-to-year

Glacier Origins and Types C. The recrystallization of snow

II. The Movement of Glaciers

II. The Movement of Glaciers Basal Sliding

II. The Movement of Glaciers Basal Sliding Plastic Flow/Internal Shearing Internal Shearing

II. The Movement of Glaciers Basal Sliding Plastic Flow/Internal Shearing

II. The Movement of Glaciers C. Crevassing (Zone of Fracture)

Crevasses

Crevasses

The Glacial Budget Zone of Accumulation Zone of Ablation Equilibrium Line

“fastest velocity at equilibrium line”

IV. Classification of Glaciers

IV. Classification of Glaciers Descriptive-based Process-based

IV. Classification of Glaciers Descriptive-based * Cirque Glaciers * Valley Glaciers * Ice Sheets

IV. Classification of Glaciers Descriptive-based Process-based 1. Dynamic classification scheme * Active * Passive * Dead

IV. Classification of Glaciers Descriptive-based Process-based 1. Dynamic classification scheme * Active * Passive * Dead 2. Thermal classification scheme * Temperate Glaciers

IV. Classification of Glaciers Descriptive-based Process-based 1. Dynamic classification scheme * Active * Passive * Dead 2. Thermal classification scheme * Temperate Glaciers * Polar Glaciers --sub polar --high polar

V. Erosional Glacial Landforms

Cirques Tarn Lakes Pater Noster Lakes Horns Aretes U shaped Valleys Hanging Valleys Fjords

Erosional Landforms

Erosional Landforms

Erosional Landforms

Cirques

Cirques……and Tarns

Arete

U-shaped valley

Hanging valley

Hanging valley

Horn

Fjords

Pater noster lakes

Glacial Erosion Glacial Striations and grooves

Glacial Polish

VI. Depositional Landforms

Glacial Till

VI. Depositional Landforms Glacial Till Stratified drift

VI. Depositional Landforms Moraines Lateral Medial

Lateral and Medial Moraines

Moraines……End, Terminal, Ground

End Moraine

Terminal moraine

Eskers, Drumlins, Kames, Kettles, Outwash Plains, Erratics

B) Drumlin –

B) Drumlin –

B) Drumlin –

C) Kettles

C) Kettles

D) Eskers

D) Eskers

Esker

Kame –

Outwash plain

The Pleistocene Epoch Milankovitch Cycles Eccentricity Tilting Wobble

Milankovitch Cycles Individual cycles vs. multiple cycles

400,000 years of change Note how climate slowly cools going into a glacial period. Then rapidly warms at the end. But quickly starts cooling again.

10,000 years of change

The Pleistocene Ice Ages: Glacial Periods Wisconsinan Illinoian Kansan Nebraskan

Global sea level drop

Pluvial Lakes

J. Harlen Bretz 1923-1932