Geology 201 Garcia Cal Poly Midterm 2

mechanical weathering

physical break down of rocks with no change to the chemical composition

Cause sheeting and exfoliation

mechanical weathering, pressure release

sheeting and exfoliation depends on

massive, homogeneous rocks

most susceptible to chem weathering

olivine

least susceptible to chem weathering

quartz

chem weathering is driven by

primary rock minerals in chemical disequilibrium with surface conditions

Translocation

movement of solid soil particles downward in solution

pedogenesis

soil formation

A horizon

leached, organic looking

B horizon

weathering product and trans-located particles

materials in b horizon

clay, calcium carbonate, iron and aluminum oxides, organic compounds

Clay

Bt

calcium carbonate

bk

iron and aluminum oxides

bs

organic compounds

bh, from a or o horizons

C horizon

unweathered parent material, unconsolidated between r and b horizons

o horizon

surface accumulation of organic matter

e horizon

lower bleach layer of A, organic acid

no

no

vertisols

Inverted soils, shrink and swell because of smectite clay sheet silicates, weak bonds between sheets, size can increase up to 100x,water gets in easily

how to vertisols happen

seasonal wet/dry, parent material is rich with smectice clays or weathered that way, poorly drained soil

lithification of detritus

1. weathering

2. erosion

3. deposition

4. compaction

5. cementation- ions precipitate out and form bonding agent

names to sedimentary rocks

1. basis of clast size

2. median diameters 2mm

3. shape

breccia vs conglomerate

breccia is angular while conglomerate is rounded. breccia close to source

shear traction

p-density of water, g- acceleration, d-depth, s=slope

where are ooilites found

underwater dunes in ne caribbean sea. east coast of florida

paleoenvironment cross beds

formed on flowing medium

condition favoring precipitation

warm temperature and agitation

contact vs regional metamorphic rocks

presence of foliation in regional rocks

hydrothermal vs contact

hydro forms where water is abundant and close to heat. contact- no water

serpentinite

mid ocean ridges, ultramafic rocks of olivine and pyroxene are converted with water at high temps. in hydrothermal

index minerals

indicate temp and pressure in rock when forming minerals were growing. indicate precise temp and pressure causing metamorphism

metamorphic facies

defined by index materials. set formed under similar conditions

foliation

predominate orientation of elongate or platy minerals formed under metamorphism

degree of foliation reflects depth of tectonic burial

slate

too small to see crystals without magnification

phyllite

too small without magnification. large enough to reflect light.

schist

crystals visible to naked eye

gneiss

segregated bands of one mineral

paired metamorphic belts

converging tectonic plates aka subduction zones. different type of rocks lining up parallel to each other

normal faults

caused by tension

reverse faults

compression

earthquake strains

elastic and brittle

focus/ hypocenter

the location of the earthquake within the earth

epicenter

location of earthquake on earths surface

p waves

horizontal motion- body wave

s waves

up and down like cracking a whip. cannot pass through liquids- body wave

love/long waves

shearing motion perp. to the direction of travel

rayleigh waves

rocking sensation of earthquake- like water waves

two types of evidence that subduction zones exist

wadati benioff zones and glaoucophane and blue schist

liquefaction

a solid material begins behaving like a liquid

liquefaction

occurs bc seismic shaking and pore fluid pressure

surface waves

long periods of oscillations

surface waves and unconsolidated material

resonance occurs bc of similar periods

surface waves and lithified rock

dampening occurs

wave velocity

wavelength / period

what causes tsunami

fault ruptures sea floor