Sedimentary Rock

Question 1

Mechanical weathering

Answer 1

breaking down to smaller pieces, each retaining characteristics of og rock

Question 2

what does mechanical weathering do to facilitate chemical weathering?

does chem.weathering help mechanical weathering

Answer 2

increases surface area (more sides) available for chem. weathering

yes

Question 3

What are four physical processes that lead to fragmentation of rock? (mechanical weathering)

Answer 3

frost wedging, salt crystal growth, sheeting, biological activity

Question 4

frost wedging
how and what kind of fragments are produced

Answer 4

water runs through cracks, freezes, enlarges cracks, angular fragments or rock weakens + fractures as ice lenses grow as it attracts liq. from surrounding pores

Question 5

Sheeting

Answer 5

entire slabs of intrusive igneous rock break loose
overlying rock gets removed (unloading), reduces pressure and, outer parts of mass expands, weathering creates exfoliation zones (slabs separate and fall off), joints are parallel to surface

Question 6

Biological activity & weathering

Answer 6

roots, burrowing animals move fresh material to surface, dying organisms produce acids (chem weathering)

Question 7

Chemical weathering

Answer 7

alter internal structures of minerals by removing or adding elements to make it more stable at surface

Question 8

Oxygen dissolved in water causes

Answer 8

oxidation (yellow-reddish-brown rust)

like iron nail in mois soil

Question 9

co2 dissolved in water is
ex of mineral

what is it produced by

Answer 9

carbonic acid (calcite gets dissolved easily)

decaying organism

Question 10

what is the residual product of feldspars? what happens to the si? residual product of quartz?

Answer 10

clay minerals
si carried away by ground water
quartz is resistant to chem.weathering

Question 11

residual product of amphibole and olivine

Answer 11

amphibole: clay minerals and iron oxides
olivine: iron oxides

Question 12

W E D A C C L

Answer 12

weathering, erosion, deposition, accumulation, compaction, cementation, lithification

Question 13

where is sediment deposited? how is it deposited by?

Answer 13

lakes, river valleys, seas, etc.
solid material settling out of a fluid

Question 14

how much sedimentary rocks account for continental outcrops? how does this relate to the crust?

Answer 14

75%
makes up the upper most layer of crust since it accumulates at the surface

Question 15

what type of rock can tell us abt earth history and is economically imp & you can find fossils in

Answer 15

sedimentary
coal

Question 16

Types of sedimentary rocks

Answer 16

detrital
chemical and biochemical

Question 17

detrital sedimentary rocks

Answer 17

sediments from solid particles f/weathered rocks

Question 18

what are the abundant minerals found in detrital rocks and why?

Answer 18

quartz (resistant to weathering, so rocks containing quartz like granite set free other grains and your left with quartz grains) and clay minerals (residue of feldspar)

Question 19

How do we distinguish detrital sedimentary rocks? name 4 categories

Answer 19

particle size: coarse, medium, fine, very fine

Question 20

conglomerate vs breccia

Answer 20

both coarse and gravel
conglomerate has rounded particles, breccia has angular ones

Question 21

what do angular vs rounded fragments indicate about distance the sediment traveled.

Answer 21

angular: not far bc edges weren’t abraded
rounded: traveled very far

Question 22

higher energy carries
og env of gravel, sand, silt and clay

Answer 22

bigger particles
gravel: rivers, rockslides, glaciers
sand: dunes, river, beaches
clay and silt: lake, lagoon, swamp

Question 23

Sandstone

Answer 23

medium
sand

Question 24

shale

Answer 24

very fine
clay

Question 25

siltstone

Answer 25

fine
silt

Question 26

chemical and biochemical sedimentary rocks

Answer 26

solution carries ion, but dissolved matter precipitates to form chem sediment

Question 27

biochemical sediments

how

Answer 27

Materials precipitated by organisms

extract mineral matter from water and form shells

Question 28

coquina

where would you find it

Answer 28

biochemical limestone of loosely cemented shell fragments

beaches, bars, and splits

Question 29

what is chalk made of

Answer 29

hard parts of microscopic organisms

Question 30

what is Travertine made of

Answer 30

inorganic limestone that forms in caves

Question 31

sedimentary rocks of microcrystalline quartz

Answer 31

chert, flint, jasper, petrified wood,

Question 32

Salt and gypsum form in

Answer 32

evaporation deposits

Question 33

what is compaction
what is it most effective in

Answer 33

when grains are pressed closer together so that pore space is reduced bc of weight of overlying material

fine grained rocks

Question 34

what is cementation

Answer 34

when water containing dissolved minerals moves through pores (precipitates, fills pores, glues)

Question 35

what is the hardest cement

Answer 35

silica

Question 36

strata

aka

Answer 36

parallel layers of sedimentary rock as sediment accumulates that varies in thickness and records env at time

beds

Question 37

what separates strata

Answer 37

bedding planes: flat surfaces where rocks tend to break

Question 38

coal vs conglomerate story

Answer 38

coal: low energy env. swamp
conglomerate: high energy env like a stream

Question 39

salt crystal growth

Answer 39

seaspray or salty groundwater penetrates through pores of rocks, evaporation leaves behind crystals that grow to enlarge cracks

Question 40

what does limestone indicate about past environment

look at env deck

Answer 40

presence of seawater (precipitation of seawater to make chemical sediment or biochemical sediments f/ marine organisms