Coastal Processes 40/41 Flashcards
define what the coast is
the area where land meets ocean
describe the different types of waves
constructive-low frequency, swash is more powerful than backwash so materials deposited
destructive- high frequency, and are high and **steep, backwash is more powerful than swash **so materials removed
name and explain the four processes of erosion
hydraulic power
abrasion
attrition
erosion
what is rock broken down by
-mechanical weathering (salt, freeze-thaw)
-chemical (carbonation)
define mechanical weathering
the breakdown of rock without changing its chemical composition
define chemical weathering
the breakdown of rock** by** changing its chemical composition
name a form of mechanical weathering
freeze-thaw weathering
- happens when the
temperature alternates
above/below** 0degrees **
- water enters rock that
has cracks e.g granite
- when the water freezes it
expands, putting
pressure on the rock.
- when the water thaws it
contracts, releasing
pressure on the rock
- repeated freezing and
thawing widens the cracks CAUSING ROCK TO BREAK UP!!
what does freeze thaw weathering do
-freezes and expands rocks, making cracks bigger
what does carbonation do
-collects alkaline rocks and causes them to dissolve
IN WARM AND WET CONDITIONS
describe the process of chemical weathering
using carbonation
-rainwater **absorbs C02 **
from the air, becoming
slightly acidic.
-carbonic acid **reacts with
rock **that contains calcium
carbonate e.g chalk or
limestone
THEN ROCKS ARE DISSOLVED BY RAINWATER
name the types of mass movement
rockfall
mudflow
rotational slip/slump
how does rockfall occur
-by mechanical weathering
how does mudflow occur
by staurated soil and weak rock flowing down a flope
**thin at top **and wide towards the bottom
how does rotational slip occur
rain water adds weight so slumps forward
what rocks form impressive cliffs
granite
limestone
chalk
as theyre more resistant to erosion
describe the process of mass movement
-the shifting of rocks and loose material down a slope e.g cliff
-happens when gravity acts on the slope
-causes coats to RETREAT RAPIDLY
when is mass movement more likely to occur
when materials full of water
-water acts as a lubricant, making the material heavier
diagram use —-
how well
characteristics of destructive waves
-a high frequency, (high and steep)
-their backwash (water moving down the beach) is more powerful than their swash (water moving up the beach)
MATERIALS REMOVED
name 3 rocks and there erosion
sedimentary- easy to erode
metamorphic- difficult to erode
igneous- difficult to erode
name a characteristic of a constructive wave
-low frequency and are low and long
-their swash is more powerful than the backwash
MATERIALS DESPOSITED
why is sediment deposited on the coast
when the water slows down and doesn’t have enough energy to carry sediment, so drops it
Water wears away the coast using what three processes
-hydraulic power
-abrasion
-attrition
how is material transported along the coast
-by longshore drift
describe the process of longshore drift
-waves follow direct of prevailing wind
-waves hit the coast at an oblique angle (not 90deg)
-swash then carries material up the beach in the same direction as waves
-backwash carries material down the beach at right angles back to the sea
-overtime material zigzags along the coast
State the processes of transportation
-traction
-saltation
-solution
-suspension
what is traction
large particles are pushed along the sea bed by the force of water
whats suspension
small particles (clay/slit) are carried along in water
what is saltation
pebble-sized particles are bounced along the sea bed by the force of water
what is solution
soluble materials (limestone) dissolve in the water and are carried along
what is deposition
the dropping of material
what is the process of hydraulic power
where waves crash against rock and compress the air into the cracks
-puts pressure on the rock
whats abrasion
eroded particles in water scrape and rub against rock, removing small pieces
whats attrition
eroded particles in water collide and break into smaller pieces becomingn more rounded
