Glacier Morphology

Ice dome - convex surface slope of ice dome

Thinner ice – steeper slope to flow
Thicker ice – lesser surface slope

On horizontal bed, h = -/2h.s
h. = 11m
s = horizontal distance from margin in metres

Ice sheet
















Valley glacier



Ice shelf















Dome of 10-50 km size
Precipitation increases with increasing altitude to summit
Dome of continental size
Increase of precipitation with altitude occurs only when near the periphery
Outlet glacier – peripheral zone of ice dome marked by radiating pattern of ice dome extending deyond dome margin within ice dome they occupies a depression & distinguished by a zone of rapidly moving ice bordered by crevasses ….ice stream

Longer glacier + gentler gradient
Greenland no mountain range, gentler gradient

Ice shelf
Models of developing principles of ice creep
Sheer cliff rising 30m above sea level
Flat surface

Accumulation
Flat upper surface
Land glaciers
Bottom freezing
Highest near the seaward edge & decreases inward

Ablation
Calving & bottom melting

Glaciers constrain by topography

Ice field
Level area of ice
Distinguished from the cap because no domelike shape
Difficult distinction between
Mountain icefield and non equilibrium ice cap
St. Elias Mountain Area, North America

Valley glaciers
Originates in icefield or cirque
Radiates from main massif, dendritic pattern simpler than rivers
Tributary glaciers joins main glacier

Hubbard glacier – 120km long
Usual size – 10-30km

Freed from constrained of valley forms piedmont lobes
Altitude high relative to size

Cirque glaciers
Accumulation from drifting snow, rigourous than larger adjacent glaciers
Plan shape of isolated cirque glacier favours strong convergent flow above EL & divergent flow below

Ice apron – thin masses of snow adhering to mountain sides
Ice fringes – bordering a coastline


Surface Ice Forms
Sastrugi – dunes of hard packed snow elongated in the direction of prevailing wind
Steeper Ice sheet Periphery

Crevasse
Surface feature related to glacier movement


Splaying crevasse


Chevron crevasse



Traverse crevasse




Life of crevasse is limited
Extensive crevassing – convex long profile
Foliation – banding in ice
Alternative layers of white bubbly ice & bluish ice