Glaciation Flashcards
define glacial
an extremely cold period of time during an ice age
define interglacial
a period of warmth during an overall period of glaciation
describe Britain in the last ice age
wooly mammoths, wolves
ice streams
extremely cold
define weathering
the breakdown of rocks in situ by the action of rainwater, biological activity and extreme temperatures
2 types of erosion
abrasion
plucking
describe abrasion
rocks at the bottom of the glacier grind against the bedrock forming sharp grooves called striations.
describe plucking
ice freezes onto large boulders which are then pulled out of the ground as the glacier advances
occurs at the back wall of corries
define erosion
the wearing down or removal of land due to flowing water, ice or wind.
glacial deposition
the glacier loses energy so it drops materials (till)
till
an unsorted mixture of materials, varies from small pebbles to large boulders
points in direction glacier moves
forms moraines
lodgement till
material deposited directly as the glacier moves forwards
ablation till
material deposited as the glacier melts
3 types of glacial transport
subglacial- material transported at the base of the glacier
englacial- material transported in the glacier
supra-glacial- material transported above the glacier
outwash
sediment carried by meltwater rivers
some outwash is rounded due to attrition by river erosion
accumulation
snow falling
build up of glacial ice due to snow being compacted into ice
ablation
snow melting
glacial ice melting during summer
explain rotational slip
snow collects on top of glacier, is heavy enough to push glacier downhill.
weight of ice on top of the glacier puts pressure on ice at the base of the glacier, so it melts
so the glacier moves by rotational slip- circular motion
when does a glacier retreat
when there is an increase in temperatures
when there is a decrease in snowfall
when ablation is greater than accumulation
snout
the end of a glacier
where does ablation occur
at the snout of the glacier
corrie formation
- snow accumulates in depressions
2.overtime snow becomes glacial ice
3.freeze-thaw weathering occurs, this produces scree
4.the scree grinds against bedrock (abrasion) so the hollow deepens due to abrasion
5.plucking occurs as the glacier moves downhill by rotational slip, this steepens the back wall
6.there’s less erosion at the front so a corrie lip forms - when ice melts, a tarn forms
3 conditions for freeze-thaw weathering
- frequent temperatures below and above 0 degrees
- supply of liquid water
- supply of rocks with cracks in them
describe freeze-thaw weathering
water gets into cracks in rocks, it freezes and expands, then it melts
the process repeats until pressure is great enough to crack the rock completely
when does a glacier advance
when accumulation is greater than ablation
decrease in temperatures
increase in snowfall
describe bulldozing
rock and debris are pushed downhill by the force of moving ice
describe rotational slip
circular movement of ice in a corrie
describe moraine
moraine is material carried and deposited by a glacier
formed by deposition
describe the 4 types of moraine
lateral- material deposited along the sides of the glacier (remain intact as they’re less likely to be eroded by meltwater)
medial- material deposited in the middle of the glacier
ground- material deposited beneath the glacier
terminal- material deposited at the end of the glacier
what is an arête
2 corries eroded back to back by plucking and abrasion to form a narrow ridge between them
E.g striding edge in Lake District
what is a pyramidal peak
multiple corries (3 or more) erode by abrasion and plucking back into the mountain forming a peak
E.g Mt Everest
what is a glacial trough
a huge U-shaped valley
formed by erosion
the glacier cuts through interlocking spurs, forming truncated spurs
some have hanging valleys and narrow ribbon lakes
flat and wide bottom, steep sides
what are:
hanging valleys?
ribbon lakes?
hanging valley is a tributary valley that is on the main valley wall, high above the main valley floor
ribbon lakes are narrow, deep freshwater lakes formed by increased vertical erosion
describe the 3 areas where erosion increases
- when a band of weaker, easily eroded rock crosses the valley
2.when a tributary glacier joins a main glacier, this increases the glacier’s mass which increases erosion
- when the valley sides become narrower
what are erratics
boulders carried by the glacier and deposited into an area of differing rock type
can originate from hundreds of miles away
what are drumlins
smooth mounds of deposited material
formed parallel to the direction of the glacier’s movement
how are hanging valleys formed
tributary glaciers flow into the main glacier
they don’t have the same erosion power as the main glacier,
so they are cut off by the main glacial valley and hang over the main valley floor
how are U-shaped valleys formed
ice fills the valley
there is erosion of both sides and the floor
valley becomes straighter as ice cuts through hard rock
the glacier has lots of power and erodes slope material which widens the valley into a U shape
tourism vs farmers conflict
tourists leave gates open-animals escape
dogs worry sheep
tourists litter- danger to animals
quarrying vs conservation conflict
quarrying destroys habitats
makes area look unattractive
tourism vs conservation conflict
tourists cause footpath erosion- makes area unattractive
more vehicles=more air pollution
energy vs conservation conflict
wind farms ruin the view
wind turbines are a danger to birds
forestry conflict
many trees of the same species reduces biodiversity
reservoirs vs conservation conflict
disrupts fish migration
displaces locals
define conservation
the act of protecting Earth’s natural resources for current and future generations
tourism in the Lake District social pros and cons
pros:
-opportunities for boating, fishing, hiking
cons:
-more vehicles =air pollution=respiratory problems
-pressure on facilities
-tourists buy holiday homes- increases price of homes for locals
tourism in the Lake District economic pros
pros:
-brings money to local businesses=multiplier effect
-50 million tourists a year
tourism in the Lake District environmental pros and cons
cons:
-air pollution from vehicles
-footpath erosion
-conflicts
management of issues of tourism in the lake district
traffic congestion-encourage public transport
go lake travel programme
footpath erosion:
-volunteer groups repair footpaths with sheep wool & stone
fix the fells project
what is quarrying
removing rocks and minerals from the ground to make products
quarrying slate in the lake district- used for roofs, gardens
pollution- air, water, noise
loss of biodiversity
habitats destroyed
