8.3 RATES OF EROSION

Question 1

what is unconsolidated sediment?

Answer 1

-material such as sand, gravel, clay and silt that has not been compacted to become sedimentary rock

Question 2

examples of igneous rocks? (3)

Answer 2

-granite
-basalt
-dolerite

Question 3

examples of metamorphic rocks? (3)

Answer 3

-slate
-schist
-marble

Question 4

examples of sedimentary rocks? (3)

Answer 4

-sandstone
-limestone
-shale

Question 5

what is igneous erosion rate?

Answer 5

VERY SLOW

Question 6

what is metamorphic erosion rate?

Answer 6

SLOW

Question 7

what is sedimentary erosion rate?

Answer 7

MODERATE TO FAST

Question 8

explanation about igneous rocks?

Answer 8

-they are crystalline
-the interlocking crystals make them strong, hard-resistant rock
-granite has few joints to there are limited weaknesses that erosion can exploit

Question 9

explanation about metamorphic rocks?

Answer 9

-crystalline metamorphic rocks are resistant to erosion
-many have foliation where crystals are orientated in one direction which produces weaknesses
-often folded and heavily fractures

Question 10

explanation about sedimentary rocks?

Answer 10

-most are clastic and erode faster
-younger rocks tend to be weaker
-rocks with bedding planes (shale) are vulnerable to erosion

Question 11

do permeable rocks allow water to flow through them?

Answer 11

-yes

Question 12

do impermeable rocks allow water to flow through them?

Answer 12

-no

Question 13

what is pore water pressure?

Answer 13

-the pressure water experiences at a particular point below the water table due to the weight of water above it

Question 14

how can satellite images be useful?

Answer 14

-they show the locations that have rocky shorelines

Question 15

why are sedimentary rocks more easily eroded than igneous? (3)

Answer 15

-sedimentary consist of loosely packed particles with variable size making them more susceptible to erosion

-sedimentary rocks have bedding planes and jointing which create weakness leading to formation of landforms such as cliffs

-sedimentary rocks have layers of strata, softer layers may erode more quickly than harder

Question 16

what are three things that protect the coastline?

Answer 16

-sand dunes
-salt marshes
-mangrove swaps

Question 17

how does vegetation stabilises sediment? (3)

Answer 17

-roots of plants bind sediment together making them harder to erode

-plants growing in sediment provide a protective layer so surface of sediment isn’t directly exposed to moving water and erosion

-plants protect sediment from wind erosion by reducing wind speed at the surface due to friction

Question 18

many plants that grow in coastal environments are ?

Answer 18

-halophytes
-xerophytes

Question 19

what can halophytes tolerate?

Answer 19

-salt water
-around their roots

Question 20

what can xerophytes tolerate?

Answer 20

-dry conditions
-those found on coastal sand dunes where sandy soil remains

Question 21

what is plant succession?

Answer 21

-changing structure of a plant community over time as an area of bare sediment is colonised by plants

Question 22

what is a sand dune ecosystem called?

Answer 22

-psammosere

Question 23

what is a salt marsh ecosystem called?

Answer 23

-halosere

Question 24

what do the pioneer plants on an embryo dune do? (3)

Answer 24

-stabilise mobile sand with root system
-reduce wind speed allowing more sand to be deposited
-add dead organic matter to sand

Question 25

how to embryo dunes alter the environment? (4)

Answer 25

-from harsh to an environment other species can tolerate
-so new plant species colonise the area
-creating fore dune
-dunes then grow upward and out to sea

Question 26

how are dune slacks created?

Answer 26

-periods of wind erosion create low areas within dune systems

Question 27

what is marram grass?

Answer 27

-example of specialised plants
-tough, long flexible leaves are designed to limit water loss by transpiration
-roots of up to 3m long that tap water below dune surface

Question 28

why are estuaries ideal for the development of salt marshes?

Answer 28

-they are sheltered from strong waves so sediment can be deposited
-rivers transport a supply of sediment to river mouth