Glacial Hydrology Flashcards
Glacier
A large, long-lasting mass of ice formed on land, that moves under its own weight
Glaciers can only form when
more snow accumulates during the winter than melts away during the spring and summer
Advancing glacier
Gains more snows than it loses
Terminus
End of glacier
Receding glacier
Negative budget, will decrease over time
Zone of accumulation
Where snow is added
Zone of ablation
Where melting occurs
Equilibrium line
Separates accumulation and ablation zones
Valley glaciers
Are confined to mountain valleys or to an interconnected system of mountain valleys
Basal slip
Movement along the base and sides
Plastic flow
Occurs only on the surface of a glacier
Continental glaciers
Cover vast areas and are unconfined by topography
What causes glaciations
Plate tectonics, variations of Earth’s orbit
hanging valleys
Smaller tributary glacial valleys left stranded high above more quickly eroded central truck valleys
Cirques
Steep-sided, half-bowl-shaped recessed carved into mountains at the heads of a glacial valleys
Aretes
Sharp ridges separating glacial valleys
Horns
Sharp peaks remaining after ciruqes have cut back into a mountain on several sides
U-shaped glacial troughs
Rivers in mountains valleys which are originally “V” shaped, eroded to “U” shapes
Fjords
Formed during previous glacial episodes when sea level was much lower; these occur at high latitudes where glaciers can be maintained even at low elevations
Plucking
Ice freezes to rock and eventually puts it lose by glacial ice movement
Abrasion
Develops glacial polish or glacial strations and produces rock flour (dust)
Till
Unsorted, unlayered glacial sediment
Laterial moraine
Elongate, low mounts of till that form along the sides of a valley glacier
Medial moraine
Form when tributary glacier comes together and adjacent lateral moraine get trapped between the two flowing ice streams
End moraine
Ridges of till piled up along the front end of a glacier
Recessional moraine
Successive end moraines left behind by a retreating glacier
Glacial outwash
Sediment deposited by water flow over, beneath and away from the ice at the end of a glacier
Glacial drift
All sediment deposited as a result of glacial activity
Stratified drift
Sorted by size and density and is layered. Generally deposited by streams which derive their sediment load from the melting glacier
Outwash plains
Formed by vast amounts of sediment carried in braided streams from melting continental glaciers
Kettle lakes
Form where blocks of ice are left in the sediment by the retreating ice
Kames
conical hills, formed where sediment is deposited in depressions on the surface of the glacier, which is then lowered to the ground surface as the glacier melts
Eskers
Comprise sediments deposited in streams running along the base of stagnant glaciers
Varves
Annual variations in sediments deposited in glacial lakes produces paired layers known as varves, which can be counted like tree rings, good data looking for climate change
What do the direction of eskers denote?
The general flow direction of water within glaciers
