midterm2, Midterm 2

igneous plutons crack in onion like....

"exfoliation" layers

sizes of detrital fragments

-coarse grained -medium grained -fine grained

characteristics of breccia rocks

-indicates a lack of transport processing -deposited close to source

sediment

-rock and mineral fragments -Shells -Minerals Precipitates

maturity

a measure of the degree of "processing"

saprolite

a rock that has been dissolved to almost nothing

formation

a sequence of strata that is sufficiently unique to be recognized on a regional scale

bed surface markings occur

after deposition while sediment is still soft

as rocks trasport they become less____________ and more_______________.

angular, rounded

physical weathering

any process that breaks rock down into smaller pieces without changing the chemistry of the rock; typically wind and water.

biological weathering

any weathering that's caused by the activities of living organisms.

graded beds

bedding layers that fine upward

water flowing over loose sediment creates

bedform

physical weathering

breaks intact rocks into unconnected clasts (detritus)

travertine

calcium carbonte precipitated from ground water where it reaches the surface

biochemical sedimentary rock

cemented shells of organisms

bedding in sedimetary structures is caused by

changing conditions during deposition

4 classes of sedimentary rocks

clastic biochemical organic chemical

sandstone

clastic rock made of sand-sized particles

weathering

combo of processes that break up and corrode solid rock, transforming it into sediment

coarse clastics

composed of gravel-sized clasts

fine clastics

composed of silt and clay

breccia

comprised of angular clasts

conglomerate

comprised of rounded clasts

jointing

cracks in rocks with no displacement

biochemical chert

cryptocrystalline quartz rock

with increasing transport, average grain size of clastic sedimentary rock ______________.

decreases

biochemical chert forms in

deep ocean basins

textural maturity

degree of roundness and sorting

mineral maturity

degree of unstable mineral removal

where is chemical weatherig absent?

deserts

reaction with water ____________ many minerals

disintegrates

intoducing water and taking away a ion

dissolution

types of chemical weathering

dissolution, hydrolysis, oxidation, and hydration

jointing

erosion occurs at high P and T, cooling and expansion occurs, fractures form along joints

evaporites are created from

evaporated seawater

granite consists of

feldspar, quartz, and biotite

transgression

flooding due to sea level rise

weathering

generation of detrius via rock disintegration

show a transition from coarse to medium to fine grain size

graded beds

individual layer of the soil profile is called_________

horizons

the atoms of most rock forming minerals are held together by

ionic

types of physical weathering

jointing, frost wedging, root wedging, salt wedging, thermal expansion, and animal attack

sedimentary rocks are usually _________ __ ___________.

layered or stratified

sediment

loose fragments of rocks or minerals broken off bedrock, mineral crystals that precipitate directly out of water, shells, or shell fragments

biochemical limestone

made from CACO3-shell remains

clastic sedimentary rock

made from weathered of rock fragments

At a subduction plate the overriding plate

may be composed of either

clast composition

mineral makeup of clasts

Rates of weathering attack very due to changes in

mineral stability, degree of compaction or cementation, subtle differences in temperature

chemical sedimentary rock

minerals that crystallize directly with water

cement

minerals that filll sediment pores

is there chemical weathering in deserts?

no

fine clastics are only deposited in

non-agitated water

soil is a _______________ resource

non-renewable

biochemical chert is formed from

opalline sillica skeletons

diagenisis

physical, chemical, and biological changes to sediment

basins occur because of

plate techtonics

hydration happens a lot in

pyrite

the most dominant mineral in sandstone

quartz

chemical weathering

reaction with water disintegrates many minerals - water is a good solvent

erosion

removal of detrius from sedimentary rocks

cross bedding is created by

ripple and dune migration

stratified

rocks have continuous layers

oxidation

rust (losing electrons)

arkose

sandstone with a lot of feldspar, less mature

0-20km

sediment cover varies in thickness from

time and transport causes

sediment evolution

where is a surface veneer thick

sedimentary basins

deltas

sediments dropped where a river enters a stream

alluvial fans

sediments that pile up at mountain fronts

clay-sized particles form

shale

silt-sized clasts are lithified to form

siltstone

dunes

similar to ripples except much larger

subsidence

sinking of land during sedimentation

detrital fragments classified by

size

water is a universal ______________, it is optimized in ________ and _______ conditions

solvent, wet, warm

weathering _______ ___ as you break it down

speeds up

a series of beds are referred to as

strata

order the following minerals from softest to hardest

talc, fluorite, quartz, corundum

clastic sedimentary rock is classified on the basis of _____________ and _______________.

texture and composition

organic sedimentary rock

the carbon-rich remains of plants

differential weathering

the process by which softer, less weather resistant rocks wear away and leave harder, more weather resistant rocks behind

sorting

the uniformity of grain size

biochemical and organic rocks

these are sediments derived from living organisms

lithification

transforms loose sediments into solid rock

multiple graded beds sequences are called

turbadites

physical and chemical

two types of weathering

assymetic ripples

undirectional flow -short, steep, downcurrent slip face

well sorting

uniform grain size

hydrolysis

water breaks cation bonds in silicate minerals

hydration

water gets sucked into bonds and forces it to explode

chemical sedimentary rocks are comprised of minerals preciitated from _________ _________

water solution

symmetric ripples

wave oscillation -sharp ridges and concave up troughs -from back and forth swash

5 elements of forming clastic sedimentary rocks

weathering, erosion, transportation, deposition, lithification

chemical weathering

when chemicals in the air, soil plants and water change rocks this is what its called

where is a surface veneer thin

where basement outcrops

poor sorting

wide variety of grain size

soil is divided into 2 zones called

zone of leeching zone of accumulation