Lithosphere Flashcards
what’s hydraulic action
the sheer force of the waves crashing onto the coast
what’s corrasion
the hurling of particles at cliff surfaces
what’s attrition
when the waves cause rocks and pebbles on the beach to smash into each other and break down in size
what’s corrosion
where the sea water dissolves particles i. the rock
describe cliff formation
-waves erode cliffs more intensely at the base
-this results in undercutting of the cliff face forming a wave cut notch
-the overhang is unsupported and eventually collapses due to gravity
-as this process is repeated the cliff face retreats leaving a gently sloping wave cut platform behind
describe headlands and bays
-headlands and bays from when there are bands of hard rock and soft rock
-the soft rock is less resistant to erosion and therefore eroded quicker to form a bay
-once a bay is formed it experiences less erosion and more deposition and therefore beaches form
-the hard rock is more resistant to erosion and therefore eroded much slower forming a headland
describe stack formation
-waves erode cliffs and headlands by the processes of hydraulic action, corrasion, attrition and corrosion
-any lines of weakness in the cliff see widened by these processes to form a crack
-this crack is then eroded further to form a sea cave
-if the waves erode all the way through the back of the cave a sea arch is formed
-the side of the arch are continually eroded until the roof of the arch becomes to heavy to be supported and collapses due to gravity
-this leaves a pillar of rock known as a sea stack
describe longshore drift
-the swash approaches the beach at an angle due to the prevailing wind direction
-the backwash flow straight back out to sea due to gravity
-therefore, particles are transported down the shore in a zig-zag pattern
describe corrie formation
-snow gathers in a north facing hollow
-after several years the snow compresses to névé and after 40-50years compresses to ice
-the ice starts to move downhill in a rotational movement due to gravity
abrasion on the bottom deepens the hollow
-abrasion is where rock stuck in the ice grind away the bedrock under it
-plucking steepens the back wall
-plucking is where ice freezes into cracks in rocks and pulls out chunks when it moves
-freeze thaw above the ice adds rock tools to it
-freeze thaw is where water gathers in cracks, freezes, expands and breaks up the rock
-there is a lip at the front of the corrie where erosion is less due to the rotational movement
-sometimes water collects in the hollow after glaciation forming a corrie loch/tarn
describe arête formation
-snow gathers in a north facing hollow
-after several years the snow compresses to névé and after 40-50years compresses to ice
-the ice starts to move downhill in a rotational movement due to gravity
abrasion on the bottom deepens the hollow
-abrasion is where rock stuck in the ice grind away the bedrock under it
-plucking steepens the back wall
-plucking is where ice freezes into cracks in rocks and pulls out chunks when it moves
-freeze thaw above the ice adds rock tools to it
-freeze thaw is where water gathers in cracks, freezes, expands and breaks up the rock
-there is a lip at the front of the corrie where erosion is less due to the rotational movement
-sometimes water collects in the hollow after glaciation forming a corrie loch/tarn
-an arête is a narrow knife-edged ride where 2 corries have eroded back to back or side by side
describe pyramidal peak formation
-snow gathers in a north facing hollow
-after several years the snow compresses to névé and after 40-50years compresses to ice
-the ice starts to move downhill in a rotational movement due to gravity
abrasion on the bottom deepens the hollow
-abrasion is where rock stuck in the ice grind away the bedrock under it
-plucking steepens the back wall
-plucking is where ice freezes into cracks in rocks and pulls out chunks when it moves
-freeze thaw above the ice adds rock tools to it
-freeze thaw is where water gathers in cracks, freezes, expands and breaks up the rock
-there is a lip at the front of the corrie where erosion is less due to the rotational movement
-sometimes water collects in the hollow after glaciation forming a corrie loch/tarn
-a pyramidal peak may form where three or more corries erode back so far that they produce arêtes with a pyramidal peak inbetween
describe U-shaped valley formation
-a glacier flow in a previously v-shaped valley
-abrasion deepens the valley floor
-abrasion is where rocks stuck in the ice grind away the bedrock
-plucking steepens the valley sides
-plucking is where ice freezing into cracks in rocks and pulls out chunks when it moves
-freeze-thaw above the glacier adds rock tools to it
-freeze-thaw is where water gathers in cracks, freezes, expands and breaks up the rock
-the glacier truncated any interlocking spurs to leave a steep sided, flat-bottomed valley
-agter glaciation a misfit stream or ribbon loch may occupy the valley
describe the formation of a drumlin
-drumlins are streamlined hills of glacial till with a steep upstream side and gentle downstream side
-there is meltwater at the base of the glacier due to friction, this meltwater saturates the sediment and allows it to be deformed by the force of the glacier flowing over the top of it, this is called subglacial sediment formation
-sometimes the glacier comes into contact with a heavier/stickier area of sediment, the glacier bunches up the upstream side and then flows over the top leaving an asymmetrical hill called a drumlin
describe the formation of an esker
-eskers are meandering ridges along a valley floor formed by meltwater streams in/or underneath a glacier
-they are made up of meltwater sands and gravels
-they are sorted by size because heavier rocks are dropped first by flowing water
-the rocks also tend to be more rounded than glacial deposits, because of the action of flowing water rounding the edges by erosion
-on reaching lower altitudes, the glacier begins to melt
-this leaves a sinuous deposit post glaciation
describe the formation of a terminal moraine
-a terminal moraine marks the furthest extent of ice
-as the glacier moves downhill it acts like a bulldozer, pushing sediment in front of its snout as it goes
-the ice melts at the snout of the glacier due to lower altitude and therefore warmer temps
-the melting ice deposits till. this is unsorted and angular
-hummocky ridges build up across the ice front
-the longer the glacier is in the same place the larger the terminal moraine will be
describe the formation of a spit
-when there is a change in the direction of the coast, longshoreman drift carries material out to sea
-over time this material accumulated until above sea level
-this leaves a hook shaped deposit called spit
describe the formation of a sandbar
-when there is a change in the direction of the coast, longshoreman drift carries material out to sea
-over time this material accumulated until above sea level
-this leaves a hook shaped deposit called spit
-if a spit grows across to another part of the coastline a sandbar results
describe the formation of a tombolo
-when there is a change in the direction of the coast, longshoreman drift carries material out to sea
-over time this material accumulated until above sea level
-this leaves a hook shaped deposit called spit
-if a spit grows out to join on to an island a tombolo results
describe the formation of a v-shaped valley
-vertical erosion cuts downwards into the valley
-the valley sides are widened by frost shattering when gravity pulls loose material into the river. this also adds to the erosive power of the river
-bedload is removed by saltation making the valley deeper
-swirling water during floods may create potholes, again cutting down into the valley
-if the river has to wind round more resistant rocks then interlocking spurs may form
