Geol Test 2

Front 1

disconformity

Back 1

rocks on either side are parrallel

Front 2

nonconformity

Back 2

intrusive igneous rock interaction with sedimentary layers

Front 3

alpha emission

Back 3

release of 2 protons, 2 neutrons--mass number reduced by four, atomic number reduced by 2

Front 4

uncomformity

Back 4

break in the rock record

Front 5

isotope

Back 5

different MASS number, same atomic number, as parent atom

Front 6

beta emission

Back 6

electron released from a neutron in the nucleus; mass number stays the same, atomic number increases by 1

Front 7

electron capture

Back 7

electron capture by nucleus, forms neutron with a proton; mass number the same, atomic number decreased by 1

Front 8

parent

Back 8

unstable radioactive isotope

Front 9

daughter product

Back 9

isotope resulting from decay of parent

Front 10

half-life

Back 10

time required for one-half of radioactive nuclei to decay

Front 11

principle of radioactive dating

Back 11

percentage of radioactive atoms that decay during one half-life is always 50%--however, actual number of atoms decreases--compare ratio of parent:daughter to yield age of sample

Front 12

radiocarbon dating

Back 12

-used to date very recent events

-produced in upper atmosphere

Front 13

geologic time scale

Back 13

eon --> era --> period --> epoch

Front 14

eons

Back 14

(youngest to oldest)

phanerozoic
proterozoic
archean
hadean

Front 15

eras of phanerozoic

Back 15

(youngest to oldest)

cenozoic
mesozoic
paleozoic

Front 16

Nicolaus Steno

Back 16

developed law of superposition

Front 17

weathering

Back 17

breakdown of rock at Earth's surface

Front 18

disintegration

Back 18

physical breakdown

Front 19

decomposition

Back 19

chemical alteration

Front 20

mass wasting

Back 20

transfer of rock and soil downslope under the influence of gravity

Front 21

erosion

Back 21

physical removal of material by mobile agents

Front 22

mechanical weathering

Back 22

-frost wedging
-unloading
-thermal expansion
-biological activity

Front 23

chemical weathering

Back 23

-dissolution
-oxidation
-hydrolysis

Front 24

dissolution

Back 24

aided by small amounts of acid in water

Front 25

oxidation

Back 25

any reaction when electrons are lost from one element

Front 26

hydrolysis

Back 26

-reaction of any substance with water
-hydrogen ion attacks and replaces other ions

Front 27

soil

Back 27

combination of mineral and organic matter, water, and air

Front 28

regolith

Back 28

rock and mineral fragments produced by weathering

Front 29

humus

Back 29

decayed animal and plant remains (smallest percentage of soil, but important)

Front 30

O horizon

Back 30

organic matter

Front 31

A horizon

Back 31

mineral and organic matter

Front 32

topsoil

Back 32

O and A horizons

Front 33

E horizon

Back 33

little organic matter--eluviation and leaching

Front 34

B horizon

Back 34

zone of accumulation

Front 35

C horizon

Back 35

partially altered parent material

Front 36

solum/true soil

Back 36

O,A,E,B horizons

Front 37

diagenesis

Back 37

chemical, physical, and biological changes that take place after sediments are deposited

recrystallization, lithification

Front 38

chemical rocks

Back 38

sediment that was once in a solution

Front 39

detrital rocks

Back 39

transported sediment as solid particles

Front 40

constituents of detrital rocks

Back 40

-clay minerals
-quartz
-feldspars
-micas

Front 41

shale

Back 41

mud-sized particles, thin layers--most common sedimentary rock

Front 42

limestone

Back 42

most abundant chemical rock--mostly calcite

Front 43

coal

Back 43

plant material --> peat --> lignite --> bituminous --> anthracite

Front 44

facies

Back 44

units of sediment accumulating adjacent to each other

Front 45

strata

Back 45

beds--most characteristic of sedimentary rocks

Front 46

stress

Back 46

force applied to a given area

Front 47

compressional stress

Back 47

shortens rock body

Front 48

tensional stress

Back 48

enlongates or pulls apart rock body

Front 49

shear stress

Back 49

slippage (deck of cards)

Front 50

strain

Back 50

changes in the shape and size of a rock body caused by stress

Front 51

strike (trend)

Back 51

-compass direction of the line produced by the intersection of an inclined rock layer/fault with a horizontal plane

-expressed as an angle relative to north

Front 52

dip (inclination)

Back 52

-angle of inclination of a surface of a rock/fault measured from a horizontal plane

-inclination and direction towards which rock is inclined

Front 53

limbs

Back 53

sides of a fold

Front 54

axis

Back 54

line drawn down points of maximum curvature of each layer

Front 55

axial plane

Back 55

imaginary surface that divides folds symmetrically

Front 56

anticline

Back 56

upfolded rock layers

Front 57

syncline

Back 57

downfolds/troughs of rock layers

Front 58

recumbent

Back 58

overturned fold

Front 59

plunging

Back 59

plunges down if anticline, up if syncline

Front 60

monocline

Back 60

large, step-like folds in otherwise horizontal strata

Front 61

dome structure

Back 61

oldest in center, youngest on flanks

Front 62

basin structure

Back 62

youngest in center, oldest on flanks

Front 63

faults

Back 63

fractures in rocks where APPRECIABLE DISPLACEMENT has taken place

Front 64

dip-slip faults

Back 64

movement parallel to dip of fault surface

Front 65

fault scarps

Back 65

long, low cliffs produced by dip-slip faults

Front 66

normal fault

Back 66

hanging wall moves down relative to footwall--lengthens crust

most are small, but can form 'fault-block' mountains

Front 67

reverse fault

Back 67

hanging wall moves up relative to footwall--greater than 45 degree dip

Front 68

thrust fault

Back 68

hanging wall moves up relative to footwall--less than 45 degree dip

Front 69

strike-slip fault

Back 69

dominant displacement is horizontal and parallel to strike of fault

Front 70

right-lateral

Back 70

as you face the fault, the opposite side moves to the right (strike-slip)

Front 71

transform fault

Back 71

large strike-slip fault that cuts through lithosphere

Front 72

joint

Back 72

fracture with no movement

most occur in relatively parallel groups

Front 73

H.F. Reid

Back 73

first explained mechanisms of earthquakes

Front 74

surface waves/L waves

Back 74

-cause greatest destruction
-complex motion
-greatest amplitude, slowest velocity
-greatest periods

Front 75

body waves

Back 75

travel through Earth's interior

Front 76

primary (P) waves

Back 76

push-pull motion

travels through solids, liquids, gases

in solids, travels 1.7 times faster than S waves

Front 77

secondary (S) waves

Back 77

shake motion

travels only through solids

slower velocity, greater amplitude than P waves

Front 78

shallow focus earthquakes

Back 78

occur along oceanic ridge system

Front 79

deep focus earthquakes

Back 79

almost all occur along circum-Pacific belt

Front 80

intensity

Back 80

measure of the degree of earthquake shaking at any given locale based on the amount of damage

Front 81

magnitude

Back 81

estimates the amount of energy released at the source of the earthquake

Front 82

Richter scale

Back 82

based on amplitude of largest seismic wave recorded

accounts for decrease in wave amplitude with increased distance

each unit: tenfold increase in amplitude, 32-fold energy increase

Front 83

moment magnitude

Back 83

derived from amount of displacement that occurs along a fault

Front 84

ground shaking

Back 84

regions within 20 to 50 kilometers of epicenter will experience same amount of shaking

Front 85

seiches

Back 85

rhythmic sloshing of water during earthquakes

Front 86

tsunamis

Back 86

seismic sea waves

vertical displacement of seafloor fault

undersea landslide