coastal systems and landsapes Flashcards
what is a closed system
a closed system is a input,transfer and output of energy but not matter.
what is an open system
input transfer and output of energy and matter
what is negative feedback
Negative feedback is when a system acts by lessening the effect of the original change and ultimately reversing it.
what is posotive feedback
positive feedback occcurs within a system where a change causes a snowball effect.
how is wind created
an area of high pressure air to low pressure air.
what is prevailing wind
prevailing wind is the direection from which the wind most commonly blows.
what is fetch
distance whihc wind blows over open water without being hit by land obstacles.
constructive waves characteristics
weather systems in the open water generate waves
long wavelength and wave period
low frequency
destructive waves
local storms are responsible for creating them
wavelength and wave period are short
wave frequency high
what is wave refraction
when a wave bends around a headland
what are tides
tides are the gravitational pull of the sea from the moon and sun.
what is the maximium tidal range
spring tides(moon and sun lined up)
what is the minimum tidal range
neap tides(when the moon and sun are at a right angle to one another)
how are waves formed
wind blowing over the sea
causes water to move in ripples
as waves approach shore they gain a circular orbit due to friction.
friction slows and steepens wave until it topples over.
what is a positive sediment budget
when there are more inputs of sediment than outputs
what is a negative sediment budget
a negative sediment budget is when there are more outputs of sediment than inputs
mass movement
the downhill movement of material under the influence of gravity.
run-off
all of the water that enters a river channel and eventually flows out the drainage basin.
marine(water) and aeolian(wind) deposition
occurs when the velocity of wind or water decreases until it can no longer carry the sediment.
describe soil creep
very slow
soil particles move down slope under gravity
caused by wetting and drying
describe mudflow
earth of mud flowing downhill usually over weak bedrock
often after heavy rainfall
water gets trapped increasing pore pressure
sudden and fast flowing so could be hazaard
describe landslide
block of rock moving suddenly downhill
materially in landslide largely intact(big blocks)
triggered by earthquake or heavy rainfall
slip surface become lubricated
describe a rock fall
sudden collapse of individual rock fragments at a cliff force
steep cliffs
mechanical weathering or earthquake
scree at bottom cliff-temporary store
describe a slump
the way it slides is curved
unconsolidated sands or clays
permeable rock overlays impermeable rock increasing pore pressure
clear sharp break
