sedimentary rocks

Question 1

what is a sediment?

Answer 1

a collection of loose earth materials

Question 2

how do sediments form?

Answer 2

when older bigger rocks break into smaller pieces
-when minerals in rock react with air/water to form new minerals
-minerals in rock dissolve in water and reprecipitate elsewhere
-animals extract dissolved mineral ions to build shells

Question 3

what are minerals precipitated out of water called?

Answer 3

sedimentary minerals,
if loose, sediment
if together, rock

Question 4

what is precipitation triggered by?

Answer 4

a change in conditions

Question 5

what is weathering?

Answer 5

the process that creates sediments

Question 6

what is physical weathering?

Answer 6

the physical breaking of big rocks into small rocks

Question 7

what is chemical weathering?

Answer 7

alter minerals and rocks as they react with air and water
-produces new minerals and dissolved elements and compounds

Question 8

what are the types of sediment texture?

Answer 8

crystalline
clastic

Question 9

what is crystalline texture?

Answer 9

minerals precipitate out of solution

Question 10

what is clastic texture?

Answer 10

broken pieces of earth material

Question 11

what are compositions of chemical sediments?

Answer 11

iron bearing crystals/ residues
microcrystalline quartz
dolomite microcrystals
calcite crystals
halite crystals
gypsum crystals

Question 12

what are biogenic sediment?

Answer 12

produced through biological activity
built out of dissolved minerals extracted from water

Question 13

types of clastic sediment?

Answer 13

siliciclastic
bioclastic

Question 14

what is siliciclastic?

Answer 14

consists of quartz and feldspar grain, rock fragments and clay

Question 15

what is bioclastic?

Answer 15

fragments of transported skeletal material

Question 16

what does source refer to?

Answer 16

the exposed rocks from which sediment forms

Question 17

what happens to sediment once it has formed?

Answer 17

it can be picked up and transported through erosion

Question 18

what are agents of erosion?

Answer 18

air, water, ice, gravity

Question 19

erosion by gravity?

Answer 19

only solid clast moves
moves large and small clasts at the same time

Question 20

erosion by air, water, ice?

Answer 20

pick up and move sediment
the more viscous, the more power to move clast

Question 21

which erosion agent has the lowest viscosity?

Answer 21

air
only move small clasts

Question 22

which erosion agent has the highest viscosity?

Answer 22

ice
moves small to large clasts

Question 23

how do clasts move from water and air?

Answer 23

rolling
saltation
traction
suspension if small

Question 24

how do clasts move in ice?

Answer 24

on top
trapped within

Question 25

how does speed affect erosion?

Answer 25

the faster it is, the more power it has to move a large range of clasts

Question 26

how are sediments deposited?

Answer 26

minerals form in situ from reaction with air/water and a rock -precipitate out of solution when conditions change -ions extracted from water to build shells/skeletons

Question 27

when is clastic sediment deposited?

Answer 27

when the agent of erosion loses its power to transport grains

Question 28

what causes agents of erosion to lose power?

Answer 28

a drop in velocity a drop in viscosity

Question 29

what is the hjulstrom diagram?

Answer 29

predicts the critical velocities at which a given grain size can be picked up, moved and deposited by WATER

Question 30

why is clay so hard to erode?

Answer 30

because clay is platy and layered and it sticks to itself

Question 31

what are the main depositional environments?

Answer 31

continental costal marine

Question 32

what are features of sedimentary structures?

Answer 32

small 3D form in sediment during or after deposition

Question 33

what is primary sedimentary structure?

Answer 33

structures form as sediment is deposited

Question 34

what is a strata?

Answer 34

most common primary sedimentary structure horizontal layers of sediment

Question 35

what are beds?

Answer 35

layers bigger than 1cm

Question 36

what are laminations?

Answer 36

layers less than 1cm

Question 37

what is a graded bed?

Answer 37

when grains become more fine

Question 38

what is cross-bedding?

Answer 38

result of deposition on inclined surfaces, produced by flowing water or wind

Question 39

what are symmetrical ripples?

Answer 39

ripples with the same angle on both sides caused by bidirectional currents

Question 40

what are asymmetrical ripples?

Answer 40

ripples with one steep side one shallow side caused by unidirectional cuurent

Question 41

what are imbricated pebbles?

Answer 41

overlapping flat pebbles due to flowing water pushing them over

Question 42

what are sole marks?

Answer 42

grooves or indents that form either from objects dragged across sediment or back current eddies scour out patches in the sediment

Question 43

what is secondary sediment structure?

Answer 43

formed after the deposition

Question 44

how are mudcracks formed?

Answer 44

when water dries up and clay minerals contract

Question 45

what is bioturbation?

Answer 45

organisms pull up sediment and erase primary structure

Question 46

what is soft sediment deformation?

Answer 46

sediment is loaded onto waterlogged sediment compression causes water to squeeze out, deforming the original bedding

Question 47

two types of lithification?

Answer 47

compaction cementation

Question 48

what is lithification

Answer 48

the process that turns sediment to stone

Question 49

what is compaction

Answer 49

due to burial, reduces pore space by forcing grains together

Question 50

what is cementation?

Answer 50

precipitation of chemical sediments in-between clasts

Question 51

characteristics of siliciclastic composition?

Answer 51

distinguished by grain size and shape

Question 52

how are chemical sedimentary rocks distinguished?

Answer 52

crystal type

Question 53

how are bioclastic rocks distinguished?

Answer 53

composed of calcite organisms grain size and shape grain type