Glaciated landscapes Flashcards
Where do most earthquakes occur ?
Around the ‘ring of fire’ surrounding the pacific ocean.
What plate boundary are most powerful earthquakes associated with ?
Conservative/ convergent.
What are Intra-plate earthquakes ?
Those which don’t happen at plate boundaries- Are often linked to hotspots or old fault lines.
what boundaries do volcanoes occur at?
convergent, divergent
Where can volcanoes be found ?
Hot spots in the middle of plates e.g. Hawii in central pacific .
How are tsunamis caused?
- By tectonic activity
- most occur due to activity at convergent boundaries.
Name the three types of plate boundaries .
Divergent
Convergent
Transform
Explain what happens at a convergent plate boundary.
Continental and oceanic :
-Denser oceanic subducts below continental.
- subducting plate leaves a deep ocean trench
- At the Benioff zone the oceanic plate is melted by the mantle
- This leads to silica being in the magma
- Built up pressure from melting plate causes explosive volcanoes which is high on the VEI , silica in the magma makes the lava more viscous which means the volcano is a Composite volcano.
Impacts = Pyroclastic flow, Tephra
Continental and Continental :
-Both plates not as dense as oceanic so lots of pressure builds.
-Ancient oceanic crust is subducted slightly , there is no subduction of continental crust.
- pile up of continental crust on top of lithosphere due to pressure between plates.
-Fold mountains are formed from piles of continental.
Oceanic and Oceanic=Underwater Volcanoes
Explain what happens at a Divergent plate boundary.
Oceanic and Oceanic:
-Magma rises between the gap left by the two plates separating, forming new land when it cools.
- Less explosive underwater volcanoes formed as magma rises.
-New land forming on the ocean floor by lava filling the gaps is known as sea floor spreading.
Continental and Continental :
- Any land in the middle of separation is forced apart, causing a rift valley.
Volcanoes form where the magma rises
-Eventually the gap will most likely fill with water and separate completely from the main island.
Explain ridge push.
the slope created when a plate moves apart has gravity acting upon it as it is at a higher elevation. Gravity pushes the plates further away, widening the gap.
Explain Slap pull.
When a plate subducts, the plate sinking into the mantle pulls the rest of the plate with it , causing further subduction.
what is ablation
the loss of mass from the glacier , e.g meltwater , avalanches , sublimation , evaporation
what is abrasion
small rocks within the base of the glacier rug against the bedrock
what is accumulation
the addition of mass to the glacier , usually as snow .
what is the active layer
the top layer of soil above permafrost, which thaws annually in summer.
what is an alpine region
areas of low temperature in high altitude , mountainous regions.
what is an Arete
A ridge formed between two corries
what is basal ice melting
the weight of a temperate glacier causes meltwater which can erode the bedrock through fluvial erosion.
what is basal sliding
glaciers sliding over bedrock due to meltwater between the two surfaces.
what is a cold based glacier
the glaciers temperature remains below zero degrees so the base of the glacier remains froze n and moves very little
What is compressional flow
Ice builds up and thickens due to the friction as a glacier travels upwards along a shallow gradient.
what is a corrie
a round hollow in the side of a hill , widened from an initial smaller hollow by a glacier within the hollow .
what are drumlins
when a glacier hits an obstacle that cannot be eroded , deposition from the underneath the glacier builds up behind the obstacle.
what are erratic’s
Boulders transported and deposited by a glacier the type of rock that forms the erratic will usually differ from the rock types in the surrounding landscapes.
what is an Esker
a long winding ridge of glacial deposition .
What is extensional flow
Ice thins out , creating crevasses, due to an increase in the glaciers velocity down a shallow gradient.
what is fluvial erosion
water within the glacier erodes the base of the glacier over time through; hydraulic action , attrition corrosion
what is frost heave
the freezing and expansion of water beneath the ground , resulting in floor uplift
what is a glacial trough
a u shaped valley formed from a v shaped river valley that becomes filled and eroded over time by a glacier .
what is a hanging valley
a valley with a wall at one end due to the glacier that filled the valley previously being low energy.
What is holocene epoch
our current glacial period of limited ice cover, lasting over 10,000 years .
what is an ice wedge
water infiltrates small cracks in the permafrost and expands on freezing repeatedly
what is an interglacial period
a period of time of warmer average global temperatures, resulting in reduced ice cover , glacial retreat and sea levels to rise
what is internal deformation
glacial movement caused by the weight of the glacier above deforming the ice .
what is a kame
a pile of material , sorted due to differing weight of sediment left on the valley floor after a glacier melts. there is three types ( Delta , terrace , pudding bowl )
what is the Milankovitch cycle
changes to the tilt (between 21 - 24.4 degrees ) and shape of the orbit ( circular= balanced warm and cold , eccentricity / elongated = colder for longer ) will affect the average temperature of the earth
what are melt water channels
streams of meltwater formed by higher temperatures
what is a Moraine
deposits of eroded material that has been transported by a glacier .Moraines may be lateral , medial , ground , recessional or terminal.
what is a nivation
erosional processes involving snow and ice.
what is orbital eccentricity
how far a planets orbit is from being a perfect circle
what is an outwash plain
material is washed out and deposited due to large volumes of melt water as a glacier recedes
what is patterned ground
is formed through the frost heave of stones in the underneath the active layer
what are periglacials
Landscapes found at the edge of glacier polar and alpine regions . permafrost occurs with low precipitation and only highly adapted plant species survive.
what is permafrost
permanently frozen soil throughout the year
what are pingos
a mound produced as ground is forced upwards through freeze thawing
what is plucking
rocks on the bedrock are frozen within the glacier . as the glacier moves the rocks are pulled from the bedrock and moved
what are Roches moutonnée’s
rocks shaped by a glacier flowing over it and eroding it.
what is solifluction
the movement of waterlogged soil trapped between active layer and permafrost.
what are solifluction lobes
as the active layer thaws, soil falls down the hillside in tongue-shaped lobes.
What are Till plains
an ice sheet detaches from the main glacier and melts, releasing all loose till and sediment across the bedrock.
what is a warm based glacier
(temperate glacier) faster travelling glaciers due to basal meltwater trapped underneath the glacier acting as lubrication to allow the glacier to move.
what are the natural causes of climate change
- stretch eccentricity
- tilt
wobble/ axial precession
what are short term causes of climate change
-variations in solar output ( sunspots - dark areas on the sun increasing solar output)
- volcanic eruptions ( solar radiation is blocked by ash )
what are the types of periglacial processes
-pingos
-patterned ground
-ice wedges
-loess
what are the types of glacial depositional processes
-Moraines :
- Medial - formed from two lateral moraines
meeting in the middle of a glacier .
- Lateral - material deposited on the side of a
glacier.
- Recessional- forms at the end of a glacier .
-Terminal - material deposited at the snout of a
glacier on valley floor
-Drumlin - elongated hills of glacial deposits
-Till plains
-Ablation till
what are the 7 different types of glacial landforms
- corries
-aretes
-pyramidal peak
-glacial tough
-truncated spurs
-hanging valley
-ribbon lakes
what are the 3 ice sheet scouring landscapes
- Roches Moutonnée
-Knock and Lochan - Crag and tail
what is a Knock and Lochan
: A scoured lowland which displays alternating Roches moutonnée
and small lakes.
what is a crag and tail
A tapered ridge of glacial deposits extended to one side.
