Coasts Flashcards
give some examples of soft rocks
clay, sand, limestone
give some examples of medium rocks
chalk (some metamorphic and sedimentary)
Give some examples of hard rock
granite, obsidian (igneous and metamorphic rock)
How is sedimentary rock formed
deposition of sediment. rock transported to a place, layers of rock build up on top of it, layers compact, harden and stick together as water is squeezed out of it.
Give some examples of sedimentary rock
sandstone, limestone
Give some examples of metamorphic rock
marble, slate, chalk
Give some examples of igneous rock
granite, obsidian
How is metamorphic rock formed
intense heat and pressure changes underground. magma heats rock, put under great pressure and is chemically changed
How is igneous rock formed
volcanic activity. molten rock solidifies. gets really hot inside earth and solidifies. how quicklu it solidifies= crystal size and rock structure
describe the features of a landslide
straight diagonal, areas of resistant material where waves erode cliff base. wave cut notch
describe the features of a slump
cliffs made of softer rock, water pulls roch down (heavier) and erodes base of cliff. scarps and curved slip planes
describe the features of a rockfall
material breaks up along bedding planes and falls down slope, rocks break off.
describe the features of a mudslide
saturated soil and weak rock flows down a slope
order the mass movements from fastest to slowest
rockfall, mudslides, landslides, slumps, soil creep
what is mass movement
shifting of rocks and loose material down a slope. happens when force of gravity acting on a slope is greater than force supporting it. more likely when material is wet. lubricates it and makes it heavier
what is a scarp
steep cut in the side of a slope
why do coastlines change over time?
-mass movement
-weathering
-erosion
-human activity
-natural hazards
-wave action
what is longshore drift
movement of sediment along a coastline. 45 degree swash, 90 degree backwash (diagonal movement)
what forms at discordant coastlines?
bays and headlands (leads to caves, arches, stacks and stumps)
give an example of a uk stack
old harry, dorset
give an example of a uk arch
durdle door, dorset
give an example of a uk wave cut platform
southerndown, south wales
what is the difference between weathering and erosion
weathering=breakdown of rock in situ
erosion=rock broken down and carried away
where is hard rock found in the uk
scottish highlands, north wales
where is soft rock found in the uk
lowland areas, cities, coasts
explain how a wave cut platform is formed
destructive waves erode foot of cliff, forming a wave cut notch. more erosion causes joint on top of notch to become unstable and collapse. collapsed material washed away, forming new wave cut notch. cliff retreats, forming wave cut platform
what causes wave cut platforms
cliff retreat and falling rock exposed at low tides
what is deposition and what effects the rate of it
water carrying sediment loses energy and slows down, dropping sediment.
-strong swash, weak backwash
-lots of transportation, more materal brought to an area
-lots of erosion, more material available to deposit
what is a constructive wave
waves that deposit material onto shore. weak backwash, strong swash. low frequency, longer and low in proportion to length
what is a destructive wave
waves that erode coastlines, weak swash, strong backwash, higher frequency, shorter, taller breaker breaks downward with great force, high in proportion to length
what causes big waves
wind dragging on the surface of water. size depends on:
-duration
-wind strength
-fetch (distance without much change in direction)
give an example of mechanical weathering
freeze thaw
give an example of chemical weathering
rain contains carbon dioxide, weak carbonic acid. erodes certain carbonated rocks, eg limestone
give an example of biological weathering
animals burrowing into soil, loosens soil, rocks also come loose. acidic bird poo. roots grow into cracks in rocks, making them biffer and breaking bits off
what is mechanical weathering?
breakdown of rock into smaller pieces without any chemical changes within the rock
what is biological weathering
the breakdown of rock through the actions of plants and animals
what is chemical weathering
breakdown of rock into smaller pieces caused by chemical changes within the rock
what is abrasion
when rocks hit against a rock wall (cliff), wearing it away
what is attrition
when rocks bash into each other and break into smaller pieces, forming smaller, more rounded pebbles
what is corrosion/solution
when chemical reactions help break down a rock/ rock wall
what is hydraulic action
water forces air further into a crack in a rock. this increases the pressure, causing the crack to expand, eventually bits of the rock break off
