weathering

Question 1

what is progressive transformation?

Answer 1

since the earth was formed 4.5 billion years, rocks have been made up and rearranged and moved elsewhere, eventually becoming part of another rock etc.

Question 2

what is the rock cycle like?

Answer 2

example of geological mass- transfer cycle. it involves the transfer of materials to different parts of the earth system.

Question 3

what are the 5 stages of rock?

Answer 3

igneous rock may weather and erode to produce sediment, which lithifies to form sedimentary rock. the new sedimentary rock may become buried and form metamorphic rock. which could then partially melt to create magma. magma then solidifies to form new igneous rock.

Question 4

what is the alternative pathway of igneous rock?

Answer 4

igneous rock could alternatively be uplifted and eroded to form new sediment and then new sedimentary rock without melting, taking a shortcut. or it could e be metamorphosed directly, without turning into sediment.

Question 5

how can material enter the rock cycle?

Answer 5

the material can enter when basaltic rock rises from the mantle. if magma erupts and forms basalt (igneous rock), and a continental hot spot volcano.

Question 6

what interactions can help the rock cycle?

Answer 6

wind, rain and vegetation gradually weathers the basalt

Question 7

how is shale produced?

Answer 7

magma erupts and forms igneous rock and a continental hot spot volcano. the interaction with wind and rain and vegetation weather the basalt, breaking it into smaller pieces and altering it to create cay. as water washes over the clay, it carries it downstream, and the river reaches the sea. the clay is deposited in the mud and gets buried and packed tightly together. this results in shale.

Question 8

what happens to shale?

Answer 8

slides below the continental shelf for millions of years, until adjacent oceanic plates subduct and the neighboring continent collides. the shale gets buried deep and as the mountain grows, the shale now moves nearer the surface, and it is metamorphosed into schist.

Question 9

what happens to schist?

Answer 9

the crust containing the schist breaks apart and splits during continental rifting. some of the schist melts and a new felsic magma forms, which raises to the surface of the crust and freezes to create rhyolite- igneous rock.

Question 10

what is weathering?

Answer 10

disintegration and decomposition of rocks and sediments by mechanical and chemical processes acting near or at the earth’s surface in situ.

Question 11

what is erosion?

Answer 11

process wehreby particles of rock or soil are detached and transported by wind, ice or fire.

Question 12

what is salt wedging?

Answer 12

growth of salt crystals. dissolves the salt in groundwater precipitates and grows as crystals in open pore spaces in the rock. pushes apart surrounding grains and so weakens the rock.

Question 13

what is thermal expansion and contraction?

Answer 13

different minerals expand an contract at different rates. when heat of an intense forest fire bakes a rock, the outer part expands. on cooling, the layers contract. this change creates forces in the rock , breaks off in sheet-like pieces.

Question 14

what is exfoliation of rocks?

Answer 14

spalling or surficial layers dye to the release of ithostatic pressure and expansion of rock. occurs as a result of chemical weathering.

Question 15

what is mechanicl weathering?

Answer 15

physical disintegration of rocks into smaller fragments. salt wedgin, thermal expansion, exfolisation, root wedging, abrasion, frosting, jointing, animal attack

Question 16

what is root wedging?

Answer 16

tree roots grow in old joints can push joints open in a process called root wedging. like breaks in sidewalks.

Question 17

what is frosting?

Answer 17

lustreless ground-glass or mat surface on rounded grains of quartz. may result in the impact of grains during wind action. freezing water bursts pipes and shatters bottles, due tow water expansion when hot. the same occurs in rocks. when water is trapped in rock, it freezes and it forces the joint open to growing.

Question 18

what is jointing?

Answer 18

rocks buried deep in the earth’s crust endure pressure due to overburden being very heavy. rocks at depth are also warmer than rocks on the surface. the squeezing of this rock decreases, and the rock becomes cooler. natural cracks form on the rock due to the removal of overburden or due to cooling. joints can break into large blocks.

Question 19

how is an animal attack mechanical weathering?

Answer 19

burrowing creatures push open cracks and move rock fragments. humans have become the most energetic agents of physical weathering. quarries, mines, roadbeds.

Question 20

what is chemical weathering?

Answer 20

alteration of change in composition of a mineral due to the action of chemical agents.

Question 21

what is included in chemical weathering?

Answer 21

dissolution, hydration reactions, relative stability of minerals during chemical weathering, hydrolysis, redox, transition metals, and organisms.

Question 22

what is dissolution?

Answer 22

the reaction between minerals and acidic or alkaline water. limestone dissolution- carbonation. some minerals dissolve rapidly only when the water is acidic. it dissolves CO2 gas in the atmosphere and it sinks down through soil containing organic debris.

Question 23

what is hydration reactions?

Answer 23

absoprtion of water. hydroysis is water breaking. causes minerals to expand.

Question 24

what is relative stability of minerals during chemical weathering?

Answer 24

not all minerals undergo chemical weathering at the same rates. in high cliamtes, it is faster. less stable.

Question 25

what is hydrolysis?

Answer 25

in the weathering of silicates, both water and carbonic acids are involved. consumes CO. weathering is the thermostat of the earth system- it controls the carbon cycle. if high CO2 increases, more weathering. if less CO2, less weathering.

Question 26

how does redox help weathering?

Answer 26

microbial action in sediment pores of water. elements lose electosn, due to the combination of oxygen. rusting of iron is an example of this.

Question 27

how do transition metals help weathering?

Answer 27

can exist in variable oxidation states. can donate or accept electrons.

Question 28

how does chemical weathering occur in organisms?

Answer 28

roots of plants, fungi, lichens, all secrete organic acids that help dissolve minerals in rocks.

Question 29

how do the 2 weatherings work together?

Answer 29

physical weathering speeds up chemical weathering. depends on the surface to volume ratio. the greater the surface area, the faster the volume of chemical weathering. if you take fresh granite and drop it, it won’t crack. take chemical weathered granite and drop it, it will crumble, therefore chemical also speeds up physical.

Question 30

what are factors that influence chemial weathering?

Answer 30

climate (temp, rainfall)
time
living organisms (acid producition, mineral decomposition)
mineral composition.

Question 31

what is soil?

Answer 31

part of regolith containing weatehred rock, water, air and humus

Question 32

why is soil important?

Answer 32

gives life. consists of rock and sediment that has been modified by weathering. interactions with organic material and rainwater- produces substrate that can support the growth of plants. soil is a type of regolith

Question 33

what is regolith?

Answer 33

debris that covers bedrock. includes both soil and accumulations of sediment that hasn’t evolved into soil yet.

Question 34

how is grain shape measured?

Answer 34

roundness and sphericity. roundness as the measure of how smooth the grain surface is depending on the transport. sphericty depends on how closely the grain shape approximates the sphere.

Question 35

what is the stage of rock maturity?

Answer 35

immature > submature > mature > supermature