8.2 Sceince

Front 1

weathering

Back 1

physical and chemical process which breaks rock down

Front 2

resaons of weatherings

Back 2

temperature change

action of water and ice

wind

living plants

crystallisation of salt

Front 3

tepmrature

Back 3

solids expand when heated

contract when cooled

if temperature change between day and night is fast this expansion and contraction can crack a rock

Front 4

ice and water

Back 4

ice can split rocks by cooling the quickly

ice also widens cracks in rocks because and water that enters will expand and freeze

Front 5

water

Back 5

water running or washing over rock can wear away the rock the rate of weathering depends on the type of rock the speed and power of water

Front 6

rivers

Back 6

rivers can cut through deep rock and create gorges

Front 7

salts

Back 7

salts can cause crystals when water evaporates

if crystals form inside rock than the expanding crystals can put a lot of pressure on the rock and break pieces of it

Front 8

wind

Back 8

fine particles of rock carried by wind can cause physical weathering the fine rock particles blast the rocks surface wearing pieces away

Front 9

plants

Back 9

plant roots can split rock

they can grow through fine cracks or creat some of there own as the root thickens the crack expands and the rock splits

Front 10

chemical weathering

Back 10

involves water and chemicals in the water and air reacting with the rock and changing it.

Front 11

gases

Back 11

air contains carbon dioxide and oxygen that can react with the rocks

makes rock change to form different chemicals that do not hold together as strongly

causes rock to crumble

colour often changes to

Front 12

acids

Back 12

rainwater contains dilute acids that attack the rock the acids can naturally form in the air during lightning but pollution also for acids in the air

known as acid rain

Front 13

water

Back 13

some rocks have soluble materials in them this means that they can be dissolved with water removing the cement that holds the rock together.

this can make the rock crumble

Front 14

erosion

Back 14

removal of weathered rock particles away from the site of weathering

Front 15

agents of erosion

Back 15

water wind ice

Front 16

erosions and weathering

Back 16

erosion is the carrying away of particles and is not the same of weathering that breaks the particles off in the first place

Front 17

sedimentation

Back 17

process of depositing eroded rock particles

Front 18

where sedimentation occurs

Back 18

where the moving water wind or ice that is carrying the particles slows down

Front 19

sedinentaton in rivers

Back 19

the slowing down of particles usually happens in the bend of rivers this is where larger rock particles are deposited

Front 20

components of soils

Back 20

sediments, living organisms decaying wastes dead leaves twigs and insects water dissolved minerals and gases

Front 21

soils

Back 21

affects plant growth vital for many organisms even humans form foundations for buildings road bridges sporting fields and other structures

Front 22

plant growth depends on these soil characteristics ?

Back 22

texture structure water holding capability permeability and consistency

also affect building

Front 23

texture

Back 23

determined by is of particles that make up the soil

Front 24

main particles of soils

Back 24

clay silt and sand and gravel

clay and silt particles are tiny

100-1000 more clay and silt particles in soil than sand in a spoonful of soil

Front 25

structure

Back 25

how well the soil particles join up to form soil clods

Front 26

crumb size in soil

Back 26

3-5 millimetre

size is important as it allows spaces called spore spaces to exist between crumbs

Front 27

pore spaces

Back 27

let water and air enter the soil to improve plant growth

Front 28

water holding capacity

Back 28

measure of how much water a particular amount of soil can hold

Front 29

soils strong

Back 29

some soils hold water very strongly so strongly that it is hard for plants to extract the water they need from them soils high in clay are like this

Front 30

clay soils

Back 30

expand when wet contract when dry damage building making them crack and unsafe

many wet clay soils are weak and cannot support buildings

Front 31

permaebility

Back 31

measure of how fast water enters the soil if water enters the soil slowly and permability is low then water is likely to run off and not enter soil

Front 32

consistency

Back 32

tendency of soil particles sticking together

clay particles are attracted to each other and stick well together while sand particles do not

Front 33

consistency farming and mining

Back 33

soils are commonly compacted by vehicle wheels the soils form a layer that sets like concrete preventing water and air from entering

Front 34

consistency sporting

Back 34

good cricket field should have at least 50% clay

watering and compacting the soil with heavy rollers make it set hard and gives a good hard surface for the ball to bounce on

soil holds together so it can last several days