other geomorph Flashcards
What is a glacier?
mass of land ice and surfical snow that persists throughout the year and is slowly moving in response to gravity and loading.
How does snow turn into glacial ice?
snow is originally randomly oriented but as they turn to ice they align. new layers of snow bury and compress the previous layers. The compression causes snow crystals to melt at the points. The water migrates down through the snow. The compressive forces cause the snow to re-crystallize, forming grains similar in size and shape to cane sugar. The grains grow larger, density increases, and the poeosity decreases. The water from melting above percolates down and refreezes resultin in spherical shapes.
What is regelation?
Motion of an object through ice by melting and freezing that is caused by pressure differnces.
What stresses cause fractures in glaciers?
compressive and extending stresses.
What is an ogive?
Alternate bands of light and dark ice seen on a glacier surface.
Why do ogives occur?
They are thought to be the result of different flow and ablation rates between summer and winter.
What are the three ways to classify a glacier?
Thermal regime, Morphology, and Dynamic Movement.
What is thermal classification of glaciers?
Temperate( wet-based) at or near pressure melting temp throughout, may have a warm base, higher flow rate.
Polar, cold-base below pressure-melting point, frozen to bed, little melting movement by plastic flow.
Subpolar, frozen to the bed, surface melting in summer.
Polythermal, a warm-based interior and a cold-based margin.
What is the morphological classification of glaciers?
ice sheets/ice caps-not constrained by topography, ice sheets large, ice caps smaller, often confined to an island or mountain range.
What is a cirque glacier?
bowl-like hollows that are found high on mountainsides that tend to be wide rather than long.
What is a valley glaicer?
Commonly formed from ice fields or cirques, They are glaciers that spill down valleys, They are very long and often flow beyond snow line.
What is a tidewater glacier?
Valley glaciers that flow far enough to reach out into the sea. responsible for calving numerous small icebergs, can cause problems in shipping lanes.
What is a peidmont glacier?
occur in steep vallies and spill onto flat plaines, spread in bulb-like bulbs. unconfined flow in lower reaches.
What controls the rate of shattering?
Temp, moisture, rock properties.
Temp-frezze thaw frequency, freezing intensity, freezing rate.
Moisture- degree of saturation, height of water table
Rock properties- tensile strength, specific surface area, porosity hydrualic conductivity.
