X1011762607-00193-53505</DOCNO> GlacierNotz GY110 Study Notes GLACIERS AND GLACIATION (Chapter 11 in Skinner and Porter) Glacier: an accumulation of ice snow and debris on land that shows evidence of motion Formation of glacial ice (p. 315) - snow falls on ice within a few weeks it is converted to small granules called FIRN (see fig 11.8) - with time and pressure of overlying ice firn recrystallizes to larger crystals Glacial Budget (mass balance p. 316) Snow accumuates in higher altitudes causing ice to flow down hill - region of new snow on the glacier = zone of accumulation Glacier flows to lower elevations with warmer climates causing melting - area of melting on the glacier = zone of melting or zone of ablation Snowline or equilibrium line marks boundary between zones of accumulation and zone of melting Fluctuations in position of terminus: - if rate of accumulation &gt; rate of melting: terminus advances downhill = glacial advance - if rate of accumulation = rate of melting: terminus remains stationary - if rate of accumulation &lt; rate of melting: terminus migrates uphill = glacial retreat How Glaciers Move: (p. 319) - internal flow: microscopic deformation along cleavage planes - basal sliding: ice slides along bedrock (or sediment) surface Types of Glaciers: (p. 310) Cirque Glacier: smallest glacier, remains high in mountains Alpine Glacier or Valley Glacier: glacier flows down a valley in a mountainous region Ice Sheet or Continental Glacier: very large ice mass that accumulates and covers much of a continent Glacial Erosion : processes Plucking: ice surrounds rocks and lifts it away from the bedrock Scour/Abrasion: rocks and debris at base of glacier abrade and erode the bedrock surface Glacial Erosional Features (Landforms) cirques: bowl-shaped depression formed by glacial plucking near a mountain peak arete: narrow ridge between two cirques horn: mountain peak containing 3 or more cirques;
(land; shows; evidence of motion Formation of glacial ice) Context(land shows,List([172, 187))):(- snow; falls; on ice; T:within a few weeks) (warmer climates; causing; melting - area of melting on the glacier = zone of melting or zone of ablation Snowline or equilibrium line marks) (bowl-shaped depression; formed; by glacial plucking near a mountain peak arete) (mountain peak; containing; 3 or more cirques) (terminus; remains; stationary) (very large ice mass; covers; much of a continent) (processes; Plucking; ) (it; is converted; to small granules) (Cirque Glacier; remains; high; L:in mountains) (ice; lifts; it; away from the bedrock) (Glacial Budget (mass balance p. 316) Snow; accumuates; L:in higher altitudes) (small granules; called; FIRN (see fig 11.8) - with time and pressure of overlying ice firn) (Glaciers; Move; ) (very large ice mass; accumulates; )
land shows,List([172, 187))
land - snow warmer climates bowl-shaped depression mountain peak terminus very large ice mass processes it Cirque Glacier ice Glacial Budget (mass balance p. 316) Snow small granules Glaciers very large ice mass
shows falls causing formed containing remains covers Plucking is converted remains lifts accumuates called Move accumulates
evidence of motion Formation of glacial ice
on ice T:within a few weeks
melting - area of melting on the glacier = zone of melting or zone of ablation Snowline or equilibrium line marks
by glacial plucking near a mountain peak arete
3 or more cirques
stationary
much of a continent
to small granules
high L:in mountains
it away from the bedrock
L:in higher altitudes
FIRN (see fig 11.8) - with time and pressure of overlying ice firn