Ch 19 Flashcards
-7% of the worlds erosion/ transportation of rock debris by glaciers.
-glaciation extent in passed was about 1/3 and now 1/10
-moving ice grids away anything in its way. Soil carried away
-bedrock polished/scraped:gouged/plucked/
abraded.
Impact of glaciers on landscape
- glacial topography/meltwater BASIS for many of the worlds lakes and ride channels.
- glaciers sculpted the alpine vistas(high glacier mountains) at heads of valleys.
- glacial deposits are the basis parent material for soils.
- glaciers cover sizable areas of earths land surface.
- deposition by ice sheets. Nice in kettle- sometimes potential lakes.
Direct impacts of glaciers
Glaciers in mountainous areas
Continental ice sheets.
Largest glacial ice today and types of glaciers
Antarctica S
Greenland N
-continental ice sheets.
Types of glaciers
Continental ice sheets
Mountain glaciers
Highland ice fields >outlets are valley glaciers.
Alpine glaciers-high in mountains
Cirque glaciers-very small alpines
Mountain glaciers
Long tongues of ice extend between rimming hills to the sea
Huge floating ice mass.
Outlet glaciers
Iceberg
May begin To develop if in a net to net year accumulation of snow in winter is greater than the amount of melting snow in summer. Each yr weighs down old snow and turns into ice. Ice moves to the pull f gravity eventually. Depends on accumulation>addition ice snow & ablation. >wasting ice melting and sublimation.
Glacial formation and movement
Snow Is changed to ice by “” and “”
Following a sequence from “” to granular snow to “” to glacial ice. “” happens by overlying newer snow on old snow.
Compression
Coalescence
Snowflakes
Neve
GLACIAL MOVEMENT
The Ice below surface of glacier (under confining pressure) “” but doesn’t break. Melting aids in movement as “” layer for sliding. Basal slip is an entire mass that slides over its bed on “” film of water & molds itself to the shape of the terrain it “”. Gravity flow, is always going “”
Deforms Slippery Lubricated Rides Forward
This erodes the landscape with IDE wedging, and freezing/thawing rock. The lower most ice melts w/friction against bedrock. Layer of water reduces “”. Water referees around rocky protrusions , exerts force as it is pushed by ice “” it. Rock particle are grasped as meltwater freezes in bedrock joints and fractures. Does wedging further loosens rock. As ice moves particles. And are plucked out while dragged along. This “” the underlying surface
Glacial plucking
Pressure
Behind it
Roughens
Bedrock is worn down by rock debris that’s dragged along in moving ice. Only “” surfaces when bedrock is of highly resistant material. This digs striations (in resistant) and “” in less resistant.
Glacial abrasion
Polished
Grooves
- bottom load transport-plucked/abraded debris.
- top load-(alpine glaciers only)
- rocks fall down high valley slopes onto ice.
- bulldozing- advancing glaciers (push) material along their front edges.
Transportation by glaciers
- All material moved and or deposited by glaciers “”
- ”” collection of debris of all sizes. Boulders to glacial flour(finely ground rock)
Two types of what?
Drift
Heterogenous
Transportation by glaciers
Rock debris deposit mites by moving/Melton ice -in sorted glimmer action of fragmented rock material.
Till