pleant earth 3

geo tome and earhtpqakels

angular disconformity

unparallel beds underneath parallel beds indicating erosion

unconformity

Parralel beds that have had erosion between them

nonconformity

sedimentary beds on an igneous or metamorphic rock

focus

point of earthquake under surface

epicenter

point on surface above earthquake focus

Cenozoic

started ~66 mya

Mesozoic

started ~252 mya

Paleozoic

started ~542

P -waves

compressional - moves through solids and liquids

S waves

sheer - moves through solid

L waves

snake like movement in horizontal plane

r waves

elliptical

L and R waves

Surface waves, most dangerous, arrive last

~3.5 billion years ago

first life form - stromatolites

~2.5 billion years ago

Cyanobacteria - first photosynthesis

magnitude

measured by amplitude of wave

elastic rebound theory

build up of strain = energy released

fossil bias towards

Marine with hard parts

Strain vs stress

putty vs stick

Strain

Deforms but bounces back

Stress

Force applied

Types of stress

tension, sheer, and compressional

tension

pulling apart found at divergent boundaries

Sheer

side by side found at transform boundaries

Compressional

squeezing together found at convergent boundaries

superposition

rocks on bottom are older

original horizontality

sedimentary rocks are originally in flat horizontal beds

Lateral continuity

in same layer are same rock and same age until sediment runs out

crosscutting

only younger rocks can cut into older rocks

Inclusions

Only pieces of older rock can be in younger rocks