lithosphere Flashcards
corrie
armchair shaped hollow with a steep backwall and rock lip
arete
narrow knife edge ridge where two corries cut back into each other
pyramidal peak
pointed peak with steep slopes with aretes where 3 or more corries cut back
glacial trough
steep sided U-shaped valley that is widened steepened and deepened
hanging valley
tributary valley that is left high above the main valley
truncated spur
steep cliff like valley sides
ribbon lake
long narrow lake in a trough
corrie lochan
small deep circular lake within a corrie
glaciation- plucking
ice freezes onto solid rock and as the glacier moves it causes pieces of rock to move with it
glaciation- frost shattering
a physical weathering process, water enter the joints and cracks in the rock and freezes as it does this it expands putting pressure onto the rock, this slowly causes angular pieces of rock to fall off and can fall down hill making scree slopes
glaciation- abrasion
morraine embedded into the base and sides of the glacier wears away the land like sandpaper
how does a glacier form
glacier forms facing away from the sun, north facing, snow accumulates which compacts into firn and then becomes glacial ice and becomes angular snow which moves down hill by gravity
what are large quantities of material called on glacier
moraine
glaciation- supragically
material carried ontop of the glacier
glaciation- englacially
material carried within the glacier
glaciation -subglacially
material carried underneath the glacier by ice or meltwater
glaciation- drift
boulders, sand and clay deposited under special conditions
glaciation- till
unsorted material of rocks sand and clay of various sizes are deposited by the glacier. its main features are erratics, morraine, drumlins
glaciation- fluvioglacial material
sorted material, main sands and gravel that are deposited by meltwater streams. its main features are eskers, kames, kettles, braided streams
glaciation- lateral morraine
carried on the surface of the glacier, comes from rockfalls on valley slopes. when the ice melts the material is dumped in a lonh line along the valleyside
glaciation- ground morraine
material dragged underneath a glacier. when deposited it forms a flat valley floor
glaciation- terminal morraine
terminal morraine is dumped at the end of the glacier. it forms and arc like ridge across the valley
glaciation- drumlins
have steep stass side with a mound of glacial fill and a gentle side with a more streamlined appearance. the direction of the ice is parallel to the movement of long axis . drumlins usually occur in groups and are though to be formed when the ice becomes overloaded with material and it was forced to deposit some, streamlining occured by later ice movement
formation of a corrie
before glaciation- snow accumulates in the north facing hollow and compacts into firn and then glacial ice
during glaciation- frost shattering contributes morraine to the glacier and plucking steepens the back wall.max erosion is where the ice is deepest and the rotational movement of morraine deepens hollow by abrasion and can form a rock lip and bershrund crevace
after glaciation- corrie lochan formed along with a scree slope as frost shattering is still present and morraine acts as a natural dam
formation of pyramidal peak and arete
before glaciation- a round top mountain is present with shallow depressions
during glaciation- the exposed part of the mountain is shattered by frost shattering and ice eats back into the hill from the corrie by plucking which will cause a ridge between to start to narrow steepen and sharpen
after glaciation- pyramidal peak is formed when 3 or more aretes meet which is formed bwteen two corries
formation of glacial trough and hanging valley
before glaciation- a v shaped valley with a main river meandering around interlocking spurs is present with tributaries
during glaciation- the main valley glaicer widens deepens steepens and straightens the valley by plucking and abrasion, the tributary valley glacier is smaller so less erosion occurs
after glaciation- steep straight spurs have been truncated a flat valley floor is present usually with a misfit stream, due to differential erosion tributary valleys are left hanging above floor of the main valley
formation of terminal morraine
as the ice moves, the glacier pushes unsorted and angular debris infront of it. the snout of the glacier can rwmain stationary for long periods of time when melting and accumulation are equal the boulder clay or till is then deposited as a ridge across the valley floor. a series of morraines will occur if the glacier retreats with pauses
formation of esker
a sinous ridge of sorted and rounded silt, sand , gravel deposited by meltwater frosting in sub-glacial channels or through tunnels of ice
how is the size of a wave determined
speed of wind, length of time the wind has been blowing, distance of sea it has travelled over
coastal-wave pounding
steep waves generate great speed as the bit foot of the cliff
coastal- hydraulic action
as a wave breaks air is compressed into cracks in the rock. the rock is loosened so that fragments are washed off.
coastal- abrasion/corasion
pebbles are repeatedly picked up from the sea bed and are hurled against the cliff wearing it away
coastal-attrition
rocks in the wave a rebashed off each other rounded and smooth
coastal- salt crystalisation
salt water enters pore spaces in the rocks and evaporates leaving crystals behind which out stress on the rock causing it to disintegrate
coastal- carbonation
rock such as limestones dissolve by slightly acidic water
coastal- frost shattering
only in exposed cold locations
coastal- biological weathering
may occur where plants grow on cracks on the rock cliff
formation of wave cut platforms
form at the foot of the cliff often at a headland where energy is maximum, erosion by abrasion corrosion pounding and hydraulic action result in undercutting the cliff to form a wave-cut notch with overhang above, this continues causing the overhang to collapse, as process repeats the cliff retreats back leaving a gently sloping wave cut platform.
the platform widens overtime and the waves break further out to sea which reduces rate of erosion and limiting growth
formation of headlands and bays
form where there is differential erosion due to alternate bands of more and less resistant rock, this coastline consists of parallel bands of hard and soft rock which are perpendicular to the sea. due to the differential erosion the bands of soft rock are eroded more quickly than the bands of resistant rock resulting in bays and headlands
formation of cave, arch, stack and stump
coasts occur where the coastline consists of hard rock and is attacked by waves along a line of weakness such as a joint. they will attack the line of weakness with hydraulic action, abrasion and solution. occasionally a blowhole will be created within the cave where compressed air is pushed upwards by the power of the wave and vertical hydraulic erosion works. overtime horizontal erosion may cut through the headland forming and arch. continual erosion may eventually cause the roof to fall leaving a stack isolated from the cliff. overtime the stack can fall due to erosion leaving a stump
formation of longshore drift
waves approach the beach at an angle because of prevailing winds, when they break swash carries material up the beach at the same angle. the backwash carries material straight back down the beach. the material then moves in a zigzag pattern and the material becomes more rounded and sorted as it travels.
formation of a sand spit
a sand spit is a long narrow section of land made of sand which extends at a gentle angle out to sea from the mainland. longshore drift moves sand along the beacj which allows material to be deposited in open water. for this the sea has the be relatively shallow to allow accumulation to occur. it eventually builds up to sea level to form an extension of the beach. as the sandspit becomes longer its rate of growth decreases because the water becomes deeper . wind from different direction can cause sand spit to become hooked.
formation of a sandbar and lagoon
if a large river drains into an estuary behind a spit it will not cross the mouth as the river current carries materials out to sea. however if there is no major river the spit may continue to grow across the bay to the next headland to form a bar. bars straighten the coastline and trap water in lagoons that cut off supply of sea water, a lagoon is a body of brackish water which often supports specialized plants and animals . the lagoon may evaporate and become filled with sediment becoming salt marsh or dry land
tombolo
a tombolo is a beach or spit which extends out to reach an offshore island. small tomolos are often only exposed at low tide
sand dune
sand dunes form along low land coasts where there is a sandy beach and alrge expanse of beach at low tide. with these conditions a low tide onshore wind picks up dry sand and moves it up the beach by saltation, the sand is moved as far as the strandline,
