Glaciers and Glacial Mechanics. I.Glacier Origins and Types.

Glaciers and Glacial Mechanics

I. Glacier Origins and Types

I. Glacier Origins and TypesA. Glacier (def): a body of moving ice that has been formed on

land by compaction and recrystallization of snow.

I. Glacier Origins and TypesA. Glacier (def): a body of moving ice that has been formed on

land by compaction and recrystallization of snow.

B. Critical Requirements

B. Critical Requirements1. Must be formed from the accumulation and ‘metamorphism’

of snow.

B. Critical Requirements1. Must be formed from the accumulation and ‘metamorphism’

of snow.2. Ice must be moving under its own weight.

B. Critical Requirements1. 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 Requirements1. Must be formed from the accumulation and ‘metamorphism’

of snow.2. Ice must be moving under its own weight.3. Must originate on land4. Persist from year-to-year

I. Glacier Origins and TypesC. The recrystallization of snow

II. The Movement of Glaciers

II. The Movement of GlaciersA. Basal Sliding

II. The Movement of GlaciersA. Basal SlidingB. Plastic Flow

II. The Movement of GlaciersA. Basal SlidingB. Plastic FlowC. Internal Shearing

II. The Movement of GlaciersD. Crevassing (Zone of Fracture)

Crevasses

Crevasses

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

“fastest velocity atequilibrium line”

IV. Classification of Glaciers

IV. Classification of GlaciersA. Descriptive-basedB. Process-based

IV. Classification of GlaciersA. Descriptive-based

* Cirque Glaciers* Valley Glaciers* Ice Sheets

IV. Classification of GlaciersA. Descriptive-basedB. Process-based

1. Dynamic classification scheme* Active* Passive* Dead

IV. Classification of GlaciersA. Descriptive-basedB. Process-based

1. Dynamic classification scheme* Active* Passive* Dead

2. Thermal classification scheme* Temperate Glaciers

IV. Classification of GlaciersA. Descriptive-basedB. 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

CirquesTarn LakesPater Noster Lakes

HornsAretes

U shaped ValleysHanging ValleysFjords

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

EccentricityTiltingWobble

The Pleistocene Ice Ages:Glacial Periods

WisconsinanIllinoianKansanNebraskan

Global sea level drop

Pluvial Lakes

J. Harlen Bretz1923-1932