Paper 1 Flashcards
(35 cards)
what are the 3 main types of weathering
mechanical,chemical and biological.
what is mechanical weathering(freeze thaw)
this is caused by repeatedly freezing of water whne it enters a crack of the rock which causes an expansion and stresses the rock. The crack slowly deppens and eventually fragment of the rocks may break off
what is biological weathering
When roots grown into the crack of a rock or when an animal burrows on cliff faces may cause rocks to weaken and decay
what is chemical weathering(acid rain)
Rain water is slightly acidic so when rain falls on rocks like limestone or chalk a weak chemical reaction occurs which causes the rock to weaken and break down
what are the 3 main mass movements
rock fall, slumping and sliding
whats rock fall
These occur suddenly when pieces of rock under a weathered cliff fall. This leads to rocks above to be unsupproted and causes it to collapse
whats slumping
Over a long period of time rainwater seeps into the permeable rock like sandstone and when it meets the impermable rock surface, the saturated soil is weakened and slumps and slides in a rotational manner along a curved surface.
whats sliding
Simular to slumping, movement of material occurs along a flat surface, usually a bedding plane. large amounts of rock and soil downslope rapidly
whats hydraulic action
when waves crash against the rock cliff, the impact causes the rockd to wear and compress air in joints and faults in rocks. As the water retreats the air is rapidly released causing the rock to weaken further.
whats abrasion
this occurs when pieces of rocks,pebbles are picked up by waves then thrown against the cliff causing pieces of rocks to fall off.
whats attrition
rock fragements or pebbles carried by the wave are reduced in size as they collide with each other and the cliff face. Eventually they are broken down into sand sized particles which are more easilt transported by the waves.
whats traction
The stones are rolled along the river bottom by the water as they are too large to transport in the water.
whats saltation
Small rocks or pebbles which are too big to be carried within the water are transported and bounce along the bottom of the river bed.
whats suspension
The sediment is probably eroded from larger rocks upstream and is then carried in the water. When the sediment is deposited from the water it is known as silt.
whats solution in transport
when minerals in rocks like chalk and limestone are dissolved in sea water and then carried in solution. The load is not visible.
whats solution in erosion
This is where a chemical reaction occurs when the wave meets the cliff as the sea water erodes the cliff as its slighlt acidic.
whats a constructive wave
When the the swash is stronger than the backwash. They normally have less engerg so the wavelnegths are longer and the waves have a shallow gradient. They result in the build up of materials as it is deposited.
whats a destructive wave
when the swash is weaker than its backwash so less sediments are depsoited than taken. The waves have a steep gradient and a short wavelength as they have more energy.
what are discordant coastlines.
Coastlines where the geology alternates between strata (or bands) of hard rock and soft rock
what are concordant coastlines
A concordant coastline has the same type of rock along its length. Concordant coastlines tend to have fewer bays and headlands.
whats longshore drift
when waves move in the direction of the prevailing wind at an angle to the beach. The swash, which carries the material, follows this same angle, but the backwash moves material vertically down the beach.
how are caves formed.
Cracks are formed in the headland through the erosional processes of hydraulic action and abrasion. As the waves continue to grind away at the crack, it begins to open up to form a cave. The cave becomes larger and eventually breaks through the headland to form an arch.
how are arches formed
caves erode further until it meets to the other end and creates an entrance where rocks start to fall due to gravity and erosion leading to ahigher arch.
how are stacks formed
from an arch, its gets higher as rocks from the cliff falls of due to hydraulic action and abrasion until gravity causes the arch to fall leading to separte stacks.
