Glaciated landscapes Flashcards
(60 cards)
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.
