sediments and rocks

Question 1

what are the different classes of sediments?

Answer 1

clastic sediments
biochemical sediments
chemical sediments
organic sediments

Question 2

what are clastic sediments?

Answer 2

mineral grains or fragments of rocks are lithified. then crystallize into a cement. compact through burial. often by silica and quartz. sandstone is an example of clastic sedimentary rock.

Question 3

what does lithification mean?

Answer 3

transform sediment or material into stone. compaction, burial, squeeze air or water out. cementations etc.

Question 4

what does erosion involve?

Answer 4

involves plucking, souring, dissolution by wind and water.

Question 5

what is transportation?

Answer 5

wind and water and ice movement. the ability of a medium to carry sediment depends on its viscosity and velocity.

Question 6

what is biochemical sediment?

Answer 6

skeletal parts, internaal, external, opal, carbonate, calcite, aragonite, bone.

Question 7

what is chemical sediment?

Answer 7

non-biogenic precipitate. evaporites.

Question 8

what is organic sediment?

Answer 8

carbon-rich. remains of a once-living animal.

Question 9

how do you classify rocks?

Answer 9

clast size: length of the diameter
clast composition: makeup of clasts of rock
angularity: degree to which grains are smooth and spherical
sorting: degree to which the clasts in the rock are the same size
nature of cement

Question 10

what do ripple marks show?

Answer 10

preserved in sandy sediment. preserve information about flow conditions. asymmetrical ripples developed from flow in ode direction. short show deep down current. long shows gentle. used to indicate ancient sediments.

Question 11

what do dunes show?

Answer 11

similar to ripples but larger. forms from water or wind transporting sand. occurs in streams and desers.

Question 12

what is glacier sediment?

Answer 12

movement of ice- moves sediment underneath it, when ice melts- its drops its load and makes a pile of glacial till.

Question 13

what is mountain stream sediment?

Answer 13

stream rush downslope in mountain avllets. fast-moving water has the power to carry large clasts.

Question 14

what is alluvial fan?

Answer 14

mountain front. fast-moving streams. the stream deposits its load of sedimnet right at the mountain front.

Question 15

what are key depoisiotnal environments?

Answer 15

marine delta environemnts- depositied at sea level. fine clastic- quiet water settings.

Question 16

what are examples of biochemical sedimentary rocks?

Answer 16

limestones
biochemical limestone
chert
biochemical chert
organic 
chalk
replacement cherk
ervapories
travertine
dolostone
dolomites

Question 17

what is limestone?

Answer 17

sedimentary rocks, calcite or aragonite. preserves fossils.

Question 18

what is biochemical limestone?

Answer 18

skeletal remains. warm, tropic shallow, clear, oxtgen rich. diverse organisms. when organism dies, their skeletal may stay in place. during transport, shells may break into smaller fragments.

Question 19

what is ancient limestone?

Answer 19

massive light grey rock that breaks into chunky blocks. organism slide in it and breaks the shells up. water passes through it and creates cement.

Question 20

what is chert?

Answer 20

rock made of crystallize quartz. after burial, silica in bottom sediment dissolves. silica in pores fluids solidifies into a gel.

Question 21

what is biochemical chert?

Answer 21

reddish. hit with a hammer and rock cracks like glass. made from cryptocrystalline quartz. forms shell of plankton.

Question 22

what is organic carbonaceous rock?

Answer 22

coal and oil shale. carbon in coal is pure carbon, but still a sedimentary rock, due to the make up of detritus in layers.

Question 23

what are the several classes?

Answer 23

evaporites, travertine, dolostone, replacement chert

Question 24

what is evaporites?

Answer 24

rocks from evaporated sea or lake water. streams brinign water into plates, carry dissolved ions. overtime, water becomes very concentrated.

Question 25

what is travertine?

Answer 25

calcium carbonate precipitates from groundwater where it reaches the surface. dissolved calcium reacts with bicarbonate. CO2 expelled into the air.

Question 26

what is dolostone?

Answer 26

limestone altered by Mg rich fluids. contains mineral dolomite.

Question 27

what is stratification?

Answer 27

the formation of strata in rock.

Question 28

what is strata?

Answer 28

sedimentary rocks are layered. arranged into beds. the boundary between 2 beds sis a bedding plate. several beds together constitute strata.

Question 29

what are bedforms?

Answer 29

the movement of the fluids creates sedimentary structures ar the interface between sediment and fluid, these are called bedforms.

Question 30

what are cross beds?

Answer 30

if you slice into a ripple or dune, you will find internal laminations that are inclined at an angle to the boundary of the main layer. these are called cross beds

Question 31

what are rift basins?

Answer 31

divergent plate boundaries, the surface of the earth subsides because the crust becomes thinner as it stretches. as the rift grows, slips on the fault.

Question 32

what are foreland basins?

Answer 32

craton side of the collision mountain belt. the form on the side of the mountains.

Question 33

what is trangression and regression?

Answer 33

sea levels change to control the succession of sediments that we see in a basin. when sea levels rise, the coast migrates inland- this is transgression. as the coast migrates, the sandy beaches migrate with it. when sea levels fall, the cast migrates seawards- this is regression.