Glaciers Flashcards
Relict glacier
Area that used to be glacial
Periglacial
Permanently cold area near a glacier/ice sheet
Glacial alpine
Glacial due to its altitude
Glacial polar
Glacial due to its latitude
Closed system
There are changes/movement of energy but not mass
Open system
Where energy and matter can exchange in and out of the system. (E.g. Glaciers)
Zone of accumulation
Area towards the top of a glacier where snow accumulates
Zone of ablation
Area towards the bottom the glacier where snow/ice breaks up or melts
Firn/névé
snow that has been compressed into ice by layers above over many years
Mass balance
Accumulation - ablation
+ve value = glacier advancing
-ve value= glacier retreating
Dynamic equilibrium
amount of input=amount of output but glacier is still moving
lithology
physical and chemical composition of the rock
bedding planes
build up of sediment layers over time causing horizontal lines in the rock
joints
vertical cracks in rock
fault
large cracks caused by tectonic movement
Continentality
if a place is coastal or inland and the changes it brings
albedo effect
snow (white) reflects heat from the sun
relief
height of the land
aspect
which compass direction a slope is facing
pressure melting point
the melting point is reduced by applying pressure
laminar flow
type of internal deformation found in cold based glaciers. The top layer of ice moves furthest as the layers under it push it along. distance accumulates as you go up the layers.
slippage
type of basal sliding found in warm based glaciers
where the ice slides over bedrock as melt water reduces friction
creep/regelation
type of basal sliding found in warm based glaciers where ice deforms under pressure and flows like plastic
bed deformation
type of basal sliding found in warm based glaciers where ice is carried along by saturated sediments on gentle gradients.
inter-granular flow
type of internal deformation found in cold based glaciers. ice crystals realign themselves under pressure to move past each other easier.
weathering
breakup of material without it being removed
erosion
breakup of material and removing it by an agent (e.g. water)
oxidation
a type of chemical weathering
minerals react with oxygen in the air creating oxides. oxides are soluble in acid making them easily weathered away.
carbonation
a type of chemical weathering
rain water + carbon dioxide = carbonic acid
acid then reacts with rock
can be a reversible reaction
solution
a type of chemical weathering
minerals dissolve into water/acid
hydrolysis
a type of chemical weathering
reaction between water and minerals in the rock producing a secondary mineral (e.g. clay)
hydration
a type of chemical weathering
water and rock form new minerals
freeze thaw
a type of physical weathering
water enters cracks and expends by up to 10% when frozen. this exerts pressure of the rock causing it to crack.
the more fluctuations of temp below 0 the more effective it is
frost shattering
a type of physical weathering
water enters porous rock and expands up to 10% when frozen. the expansion causes the rock to shatter from the inside.
pressure release
a type of physical weathering
as a glacier retreats, the pressure put on the rock releases causing it to expand back to the original level
this causes pseudo bedding planes
tree roots (weathering)
a type of biological weathering
tree roots grow in cracks and joints in rock. the pressure exerted caused the pock to crack more.
when trees fall, their roots pull up soil and rock
organic acids/chelation
a type of biological weathering
acids produced by decomposition of organic matter react with rock
some algae have the same effect
rockfall
Type of mass movement
rock loosened from a cliff and fall (gradient steeper than 40 degrees)
sliding
Type of mass movement
a section of rock/soil/snow slides down a slope as 1 large mass.
plucking
type of glacial erosion
melt water seeps into joints on the valley floor due to pressure. As it seeps in, pressure is released and it freezes again, sticking to the rock. as the glacier advances, it pulls the rock away from the bedrock.
Abrasion
as the glacier advances, sub-glacial debris scrapes at the bedrock, acting like sandpaper and creating striations.
rock flour
fine rock dust created by the erosion of the sub glacial debris
nivation
not classified as weathering or erosion
involves;freeze thaw, solifluction, and transport by running water
supraglacial
debris carried on top of the glacier
englacial
debris carried within the ice
subglacial
debris carried at the bottom of the glacier (moved down through the glacier or picked up by abrasion/plucking)
drift
all debris deposited by glaciers
till
debris deposited specifically by the glacier
outwash/glacio-fluvial
debris deposited by meltwater
lodgement till
material deposited by advancing ice due to downward pressure forcing the till into the valley floor
ablation till
material deposited by meltwater from stagnant or retreating glaciers
unsorted
the glacier deposits all the till at once instead of in size order like in rivers
0o..o0o.0..o0..
unstratiified
the deposited material forms no distinct layers e.g. 0o.o0..0 ..oo0o.0 0.ooo00.
roche moutonne
Landform with a smooth incline on one side which was created by abrasion and a steep jagged side caused by plucking.
I large chunk of rock left after a glacier moved over an incline a plucked the back of it
striations
scratches/grooves caused by abrasion, pointing in the direction of ice flow
lateral moraine
ridge of till running parallel to a glacier
end moraine
ridge of till deposited at the end of a glacier
medial moraine
ridge of till deposited between 2 glaciers (like a lateral moraine but stuck between 2 glaciers)
recessional moraine
type of end moraine but is caused by glacier retreating and then staying in dynamic equilibrium for a significant amount of time, causing an end moraine. there may be several running perpendicular across the valley
terminal morraine
type of end moraine but is the moraine furthest down the valley
erratic
boulder with different geology to the surrounding area
till sheet
large area of till deposited by a retreating ice sheet
