Glaciers and Glacial Mechanics

I.Glacier Origins and Types

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

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

1.Must be formed from the accumulation and ‘metamorphism’ of snow.

B. Critical Requirements 1.Must be formed from the accumulation and ‘metamorphism’ of snow. 2. Ice must be moving under its own weight.

B. Critical Requirements 1.Must be formed from the accumulation and ‘metamorphism’ of snow. 2.Ice must be moving under its own weight. 3.Must originate on land

B. Critical Requirements 1.Must be formed from the accumulation and ‘metamorphism’ of snow. 2.Ice must be moving under its own weight. 3.Must originate on land 4.Persist from year-to-year

I.Glacier Origins and Types C. The recrystallization of snow

II. The Movement of Glaciers

A.Basal Sliding

II. The Movement of Glaciers A.Basal Sliding B.Plastic Flow

II. The Movement of Glaciers A.Basal Sliding B.Plastic Flow C.Internal Shearing

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

Crevasses

III.The Glacial Budget Zone of Accumulation Zone of Ablation Equilibrium Line

“fastest velocity at equilibrium line”

IV. Classification of Glaciers

A.Descriptive-based B.Process-based

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

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

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

IV. Classification of Glaciers A.Descriptive-based B.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

Cirques

Arete

U-shaped valley

Horn

Fjords

Moraines Lateral Medial VI. Depositional Landforms

Glacial Till VI. Depositional Landforms Stratified drift

Lateral and Medial Moraines

Moraines……End, Terminal, Ground

End Moraine

Terminal moraine

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

Drumlin

Esker

Outwash plain

The Pleistocene Epoch Milankovitch Cycles Eccentricity Tilting Wobble

The Pleistocene Ice Ages: Glacial Periods Wisconsinan Illinoian Kansan Nebraskan

Global sea level drop

Pluvial Lakes

J. Harlen Bretz