1.3 Lithosphere Flashcards
Corrie
Snow accumulates on north facing mountain hollows
Occurs when more snow falls in winter than summer
Snow lies longer on shaded north facing slopes, compacted into neve, then ice
Mountain erodes from plucking- ice freezes on bedrock, pulling loose rocks away from backwall
Abrasion- rocks in glacier grind away at the bedrock and deepen it
Frost shattering- water in rock cracks, freeze and expand, weakening rock until fragments break
Glacier moves downhill due to gravity and crevasse opens up at back of hollow
Meltwater and rock reach bottom of glacier, adding to erosive power
Glaciers weight causes rotational sliding, deepens and widens hollow
Increased friction slows glacier at edge of corrie, leaving a rock lip- eg. Brown Cove
Arete + Pyramidal Peak
Snow accumulates on north facing mountain hollows
Occurs when more snow falls in winter than summer
Snow lies longer on shaded north facing slopes, compacted into neve, then ice
Mountain erodes from plucking- ice freezes on bedrock, pulling loose rocks away from backwall
Abrasion- rocks in glacier grind away at the bedrock and deepen it
Frost shattering- water in rock cracks, freeze and expand, weakening rock until fragments break
Glacier moves downhill due to gravity and rotational sliding deepens the hollows
Occurs when two corries back to back erode towards each other
Ridge becomes knife-edged, leaving a scree slope
Three or more glaciers back to back forms a high triangular peak- eg. Striding Edge
U Shaped Valley + Hanging Valley + Ribbon Lake
Snow accumulates on north facing mountain hollows
Occurs when more snow falls in winter than summer
Snow lies longer on shaded north facing slopes, compacted into neve, then ice
Mountain erodes from plucking- ice freezes on bedrock, pulling loose rocks away from backwall
Abrasion- rocks in glacier grind away at the bedrock and deepen it
Frost shattering- water in rock cracks, freeze and expand, weakening rock until fragments break
Glacier moves downhill due to gravity and follows path of v shaped valley
Glacier ploughs through interlocking spurs as it moves downhill, leaving truncated spurs
Steep valley sides creates shape of glacial trough and misfit stream no longer fits valley floor
Soft bedrock eroded quickly leaving ribbon lake when glacier melts- eg. Glencoe
Drumlin
Streamline, elongated hills made of glacial till and boulder clay
Unsorted layers of sediment as glacier deposits all sizes of sediment at once
Deposition occurs underneath glacier as ice moves downhill due to gravity
Glacier becomes overloaded with sediment and loses energy to carry it
Melted ice at bottom of glacier deposits material and glacier streamlines it when it flows over
Obstacle on ground acts as trigger point and sediment builds up around it
Esker
Meandering ridges on a valley floor formed by meltwater streams at the bottom of a glacier
Meltwater is composed of sand and gravel and is sorted by size
Heavier particles dropped first by flowing water as stream loses energy to carry them
Stones are rounded due to flowing water eroding and smoothing the edges
When ice melts, glacial streams deposit materials in tunnel until there is a build up
Load deposited on channel bed creating long and narrow esker
Terminal Moraine
Ridge on a valley composed of glacial till and boulder clay
Glacier moves downhill due to gravity and pushed unsorted material in front of snout
When ice melts, the glacier loses energy and deposits moraine
Terminal moraine is the furthest point the glacier reaches so material is left to build up
Wave Cut Platform
Sea attacks a weakness in base of cliff like a fault
Notch created by hydraulic action- waves compress trapped air in rocks, weakening rock
Abrasion- rock fragments thrown against rock is worn away
Solution- carbonic acid in sea water dissolves rock
Attrition- rock ground down by wave friction into small, fine particles
Rock overhangs above notch and enlarges from erosion until it collapses from its weight
New cliff face erodes from high tide and retreats inland
Gently sloping rocky surface extends out to sea away from cliff- eg. White Cliffs of Dover
Headland and Bay
Bands of soft and hard rock are eroded and soft rock erodes quicker forming a bay
Bay created by hydraulic action- waves compress trapped air in rocks, weakening rock
Abrasion- rock fragments thrown against rock is worn away
Solution- carbonic acid in sea water dissolves rock
Attrition- rock ground down by wave friction into small, fine particles
Hard rock more resistant to erosion and jut out into sea as exposed headlands
Sandy beaches are sheltered bays where wave loses energy so deposit material
Often form in areas with discordant coastlines and are right angled to coast- eg. Swanage Bay
Cave + Arch + Stack
Sea attacks a weakness in cliff like a fault
Weak point eroded by hydraulic action- waves compress trapped air in rocks, weakening rock
Abrasion- rock fragments thrown against rock is worn away
Solution- carbonic acid in sea water dissolves rock
Attrition- rock ground down by wave friction into small, fine particles
Lines of weakness become larger and develop into caves
Erosion on both sides of headland until sea cuts through walls of cave creating an arch
Base of arch is undercut and is unsupported, collapses due to gravity forming a stack- eg. Old Harry
Spit
Formed by longshore drift
Prevailing wind makes swash waves carry material up beach at an angle
Backwash waves dragged back due to gravity at a right angle
Change in direction of waves on coastline creates spit with a sheltered area for deposition
Material accumulates until it appears above water
Carries on developing if deposit is greater than the erosion
Spit may have a hooked end when wind directions change
Salt marsh forms in sheltered area behind spit- eg. Spurn Head
Sand bar
Formed by longshore drift
Prevailing wind makes swash waves carry material up beach at an angle
Backwash waves dragged back due to gravity at a right angle
Change in direction of waves on coastline creates spit with a sheltered area for deposition
Material accumulates until it appears above water
Carries on developing if deposit is greater than the erosion
Spit grows across to other end of bay to seal two headlands with a lagoon behind it
Salt water lagoon may fill up due to build up of sediment- eg. Slapton Sands
Tombolo
Formed by longshore drift
Prevailing wind makes swash waves carry material up beach at an angle
Backwash waves dragged back due to gravity at a right angle
Change in direction of waves on coastline creates spit with a sheltered area for deposition
Material accumulates until it appears above water
Carries on developing if deposit is greater than the erosion
Spit will connect to an island to form a tombolo
Occurs when spit extends out from mainland and seals with island- eg. St Ninian’s Isle
