Geology Exam 3

Front 1

Groundwater

Back 1

water found in sediment & fractures in bedrock

-largest freshwater resource available to humans (makes up majority of non-frozen freshwater) (second after glaciers when including all freshwater)

-sustains streams during dry periods
[stores rainwater]

-makes sinkholes and caves (removal of limestone)

-moves only a few CM / day

-powered by energy from gravity
--->allows water to move from where h2o table is high to where it is low

Front 2

rate of exchange for groundwater
v
rivers

Back 2

rate of groundwater exchange:
280 YEARS

rate of exchange for rivers:
11 DAYS
[w/o rain river would run dry in 11 days]

Front 3

distribution of groundwater

Back 3

*more steep = less groundH2O

ZONE OF AERATION:
1)belt of soil moisture
2)capillary fringe
{can't be pumped into wells bc clings to rock}

ZONE OF SATURATION:
1)WATER TABLE
(upper limit of saturation zone & ground water)

Front 4

belt of soil moisture

term

Back 4

the water in the near surface zone

-doesn't travel far due to molecular attraction at surface --->film on soil particles
*where roots and organic matter are

Front 5

zone of saturation

term

Back 5

where all pore spaces are completely filled w/H2O

-water within zone of saturation = GROUNDWATER!

-the upper limit = water table

Front 6

capillary fringe

term

Back 6

where "groundwater" is held by surface tension in passages between grains of soil/sediment

Front 7

zone of aeration

term

Back 7

the area above water table including ccapillary fringe and belt of soil moisture

-water here can't be pumped by wells b/c it clings to rock/soil

Front 8

water table variations

Back 8

-depth is highly variable
-varies seasonally & from yr to yr due to changes in rainfall

-not flat
-->resembles surface topography
-moves slowly & "piles up" beneath high areas
(if rain ceased, H2O"hills" would decrease and reach valley level)

Front 9

"gaining streams"

Back 9

streams gain water from groundwater

-water table must be at higher elevation than surface of stream

*most common*

Front 10

"losing stream"

Back 10

stream loses water to groundwater

-water table elevation must be lower than surface of stream

Front 11

porosity influencing groundwater

Back 11

porosity = % of total volume that consists of pore spaces

Front 12

permeability

Back 12

the ability to transmit a fluid

-smaller the pore spaces slower water moves

groundwater divided into:
1)specific yield
2)specific retention

Front 13

specific yield

Back 13

the portion of groundwater that will drain under influence of gravity

*indicates how much water is actually available for use

[ex. clay's porosity = high; spaces small = h2o can't move thru it = LOW specific yield]

Front 14

specific retention

Back 14

groundwater that's retained as film on surfaces and in tiny openings

*indicates how much water is bound in material

Front 15

aquitards

Back 15

impermeable layers hindering or preventing h2o movement

*CLAY*

Front 16

aquifers

Back 16

permeable rock that transmits groundwater freely

*SANDS & GRAVELS*

Front 17

Spring

Back 17

natural outflow of groundwater resulting from when water table intersects earth's surface

also result when aquitard blocks downward movement and forces it laterally ->spring results where bed is outcropped

also a small aquitard can prevent a portion of water intercepted creating localized zone of saturation & a PERCHED water table

Front 18

perched water table

Back 18

localized zone of saturation above the main water table
-->created by impermeable layer [aquitard]

Front 19

hot springs

Back 19

result from grounwater circulated and heated at great depths

*water = 6-9*C warmer than avg air temp

-source of heat for most = cooling igneous rock
---->most in WEST!

Front 20

Geysers

Back 20

intermittent hot springs
-water ejected then steam
-occur where extensive underground chambers exist w/i hot igneous rock

PROCESS:
-cool groundwater enters chamber
-heated by surrounding rock
-great pressure prevents it from boiling
-heating of water causes expansion
-some forced out at surface
-loss of water reduces pressure on remaining water
-->lowering the boiling point
-portion of h2o deep w/i chamber turns to steam and geyser erupts

(groundwater heats, expands, turns to steam, erupts)

Front 21

aquifer

Back 21

underground bed / strata that yields water

Front 22

Well

Back 22

hole penetrating into the zone of saturation

-to ensure continuous water supply hole must penetrate below the water table

Front 23

drawdown

Back 23

the effect of the water table lowering around a well when water is withdrawn from it

-decreases w/ distance from well

-results in a depression in the water table (a cone of depression)

Front 24

cone of depression

Back 24

a depression in the water table resulting from the drawdown effect from a well

-->increases hydraulic gradient near well --> water flows more rapidly toward opening

-->causes nearby shallow wells to become dry

Front 25

problems associated w. groundwater withdrawal

Back 25

1)treating groundH2O as nonrenewable
-h2o available to recharge aquifer often less than amt being withdrawn

2)subsidence {to sink lower than normal levl}
-ground sinks when h2o pumped out faster than its recharged

3)saltwater contamination
-saltwater is drawn into wells, contaminating supply
-major problem in coastal areas

-freshwater less dense than saltwater...floats on top
-water table 40x greater below sea level than above sea level
-excessive pumping lowers water table ==> the bottom of freshwater zone rises by 40x that amount

*also as more surface is covered by parking lots/buildings/etc
--->reduction in h2o infiltration

Front 26

groundwater contamination

Back 26

sewage = common source
-increasing # of septic tanks
-can become purified after passing thru few dozen meters of sand or permeable sandstone
-gravel and other really permeable aquifers have large pores thus groundH2O can travel LONG distances w/o being cleansed

-a sinking well -->cone of depression-->steeper slope-->faster movement of water--->
*Original Slope Can Be Reversed!*
*faster movement of water can also allow for less time for water to be purified*

-fertilizers
-pesticides

Front 27

caverns

Back 27

created when slightly acidic groundwater dissolves limestone in zone of saturation

Front 28

groundwater dissolves rock when...

Back 28

groundwater contains carbonic acid (when rainwater dissolves carbon dioxide)
-carbonic acid reacts w/calcite in limestone

Front 29

dripstone

Back 29

(travertine) - found w/i caverns

-calcite deposited as carbon dioxide evaporates from water

-collectively called speleothems

Front 30

speleothems

Back 30

-the various dripstone features found in caverns
-no two exactly alike

types:
1)stalactites
2)stalagmites

Front 31

stalactites

Back 31

type of speleothem

-hang from ceiling
-carbon dioxide escapes from drop and calcite precipitates
-hollow limestone tube created [SODA STRAW]

Front 32

stalagmites

Back 32

type of speleothem

-form on floor of cavern and reach toward celing
-don't have central tube
-more massive

*given enough time stalactite and stalagmite can form a column

Front 33

karst topography

Back 33

landscapes that have been shaped by dissolving forces of groundwater

-areas typically have irregular terrain punctuated with sinkholes
-lack surface drainage (streams)
--->after rain water funneled below ground thru sinks -- flowing through caverns until reaching the water table

Front 34

sinkholes (sinks)

Back 34

depressions
formed by:
1)gradually without physical disturbance ->limestone just below soil dissolved by freshly charged rainwater
-shallow w/gentle slopes

2)abruptly when roof of cavern collapses under its own weight
-steepsided & deep

Front 35

Glaciers

Back 35

thick mass of ice originating on land from accumlation, compaction, & recrystallization of snow
-cover ~10% of earth's land surface
-h2o stored as glacial ice for tens, hundreds, thousands of years
-powerful erosional force
--->accumulates, transports, deposits sediments
(they FLOW)

Front 36

Valley / Alpine
Glaciers

Back 36

-exist in mountainous areas
-flows down valley from accumulation center at head

-advange a few CM / day
-stream of ice bounded by rock walls
-widths usually small compared to length

Front 37

Glaciers

Back 37

thick mass of ice originating on land from accumlation, compaction, & recrystallization of snow
-cover ~10% of earth's land surface
-h2o stored as glacial ice for tens, hundreds, thousands of years
-powerful erosional force
--->accumulates, transports, deposits sediments
(they FLOW)

Front 38

Valley / Alpine
Glaciers

Back 38

-exist in mountainous areas
-flows down valley from accumulation center at head

-advange a few CM / day
-stream of ice bounded by rock walls
-widths usually small compared to length

Front 39

Formation of glaciers

Back 39

-form in areas where more snow falls in winter than melts in summer

STEPS:
-air infiltrates pores in snow crystals
-water vapor condenses
-->snowflakes become smaller, thicker, spherical
(& large pores disappear)
-air has been forced out and snow has recrystallized into a denser mass of small grains [FIRN]
-more snow = pressure increases
-->when thickness exceeds 50 M weight fuses firn into solid mass of interlocking ice crystals
-> GLACIAL ICE

*snowflakes smaller, thicker, spherical; air forced out; recrystallized into grains -FIRN; thickness exceeds 50 M -becomes glacial ice

Front 40

Firn

Back 40

granular recrystallized snow

-denser mass of coarse grains
w. consistency of sand

Front 41

transformation of snow to ice

Back 41

snowflake

granular snow

firn

glacial ice

Front 42

2 types of glacial "flow" (movement)

Back 42

1) plastic flow

2) basal slip

Front 43

plastic flow

Back 43

-movement WITHIN the ice
-ice behaves as brittle solid until pressure exceeds 50 M then behaves as plastic (silly putty)

-glacial ice = molecules stacked on eachother
-bonds between layers weaker than bonds w/i layers
-->LAYERS SLIDE OVER ONE ANOTHER

Front 44

basal slip

Back 44

-entire ice mass slips on ground
-most glaciers flow by this process
-occurs in discrete "JUMPS"

-meltwater acts as hydraulic jack / lubricant helping ice over rock

-temperatures can be increased by friction from plastic flow --> glacier moves by both plastic flow & basal slip

Front 45

zone of fracture

Back 45

uppermost zone
-top 50 M (can't move by plastic flow)
-brittle
-carried along "piggyback" style by ice below
-when glacier goes over irregular terrain the zone is subjected to tension, creating fractures
-->cracks/ crevasses

Front 46

crevasses

Back 46

cracks that form in zone of fracture when subjected to tension from moving over irregular terrain
-can extend to 50 M
(below 50 M plastic flow seals them off)

Front 47

basal slip

Back 47

-entire ice mass slips on ground
-most glaciers flow by this process
-occurs in discrete "JUMPS"

-meltwater acts as hydraulic jack / lubricant helping ice over rock

-temperatures can be increased by friction from plastic flow --> glacier moves by both plastic flow & basal slip

Front 48

zone of fracture

Back 48

uppermost zone
-top 50 M (can't move by plastic flow)
-brittle
-carried along "piggyback" style by ice below
-when glacier goes over irregular terrain the zone is subjected to tension, creating fractures
-->cracks/ crevasses

Front 49

crevasses

Back 49

cracks that form in zone of fracture when subjected to tension from moving over irregular terrain
-can extend to 50 M
(below 50 M plastic flow seals them off)

Front 50

basal slip

Back 50

-entire ice mass slips on ground
-most glaciers flow by this process
-occurs in discrete "JUMPS"

-meltwater acts as hydraulic jack / lubricant helping ice over rock

-temperatures can be increased by friction from plastic flow --> glacier moves by both plastic flow & basal slip

Front 51

zone of fracture

Back 51

uppermost zone
-top 50 M (can't move by plastic flow)
-brittle
-carried along "piggyback" style by ice below
-when glacier goes over irregular terrain the zone is subjected to tension, creating fractures
-->cracks/ crevasses

Front 52

crevasses

Back 52

cracks that form in zone of fracture when subjected to tension from moving over irregular terrain
-can extend to 50 M
(below 50 M plastic flow seals them off)

Front 53

rate of glacial movement

Back 53

-several meters / day
-valley glaciers experience friciton on sides --> rate of flow greatest in center
-can experience surges

Front 54

surges

Back 54

periods of extremely rapid movements then returning to normal rate
-as much as 100x normal rate

-could be caused by increase water pressure reducing friction & increasing basal slip

Front 55

zone of accumulation

Back 55

where snow accumulation and ice formation occur

-->outer limits = snowline

Front 56

snowline

Back 56

the outer limit of the zone of accumulation

-elevation varies greatly
(polar regions @ sea level, tropical regions @ high elevations)

Front 57

zone of wastage

Back 57

beyond the snowline
--where there is a net loss to the glacier
(snow from previous winter melts, as does some of glacial ice)

wastage due to
1)MELTING
2)CALVING

Front 58

calving

Back 58

occurs in zone of wastage

-large pieces of ice break off the front of the glacier

-responsible for icebergs (when near ocean/lake)
-->icebergs SLIGHTLY less dense than water = 80% mass underwater

Front 59

glacial budget

Back 59

the balance between accumulation @ upper end and loss @ lower end

-if accumulation exceeds ablation the glacial front advances until ablation and accumulation are balanced

-if ablation exceeds accumulation the ice front will retreat & zone of wastage diminishes
(although ice within glacier still flows forward)
->shrinks from both ends

Front 60

ablation

Back 60

the loss at the lower end of the glacier
(in zone of wastage)

Front 61

glacial erosion

Back 61

capable of great erosion & transport, more than any other erosional force
(& much faster)

-ice doesn't allow debris to settle out like streams & such

Erode in 2 ways:
1)PLUCKING
2)ABRASION

Front 62

Plucking

Back 62

-the lifting of rocks

-loosens and lifts rock incorporating them into ice
-happens when meltwater penetrates cracks in bedrock beneath glacier and freezes

Front 63

Abrasion

Back 63

rocks w/i ice act as sandpaper to smooth/polish rock below

-pulverized (powdered) rock produced = rock flour

Front 64

rock flour

Back 64

when rocks in bottom of glacier produce pulverized rock / rock powder

-->can cause glacier to appear gray / milky

{PRODUCED BY GLACIAL ABRASION - friction}

Front 65

glacial striations

Back 65

scratches & grooves gouged into the bedrock

-gives clues to direction of ice flow

-caused by large rocks in ice @ bottom of glacier

{PRODUCED BY GLACIAL ABRASION - friction}

*doesn't always do this however.... can also polish the rock beneath

Front 66

landforms created by glacial erosion
LIST

Back 66

glacial trough
truncated spurs
hanging valleys
pater noster lakes
cirques
tarns
fiords
aretes
horns

Front 67

GLACIAL TROUGH

(landform by glacial erosion)

Back 67

the U shaped broader/deeper valley

-changes the V-shaped valley created by streams into U-shaped trough
-straightens the valley

Front 68

TRUNCATED SPURS

(landform by glacial erosion)

Back 68

triangular shaped cliffs

-created by the removal of spurs of land extending into glacial valley

Front 69

HANGING VALLEYS

(landform by glacial erosion)

Back 69

valleys left standing above the main glacial trough

-due to the fact that deepness of glacial erosion depends on thickness of ice
-valleys feeding into main trough not as deep

Front 70

PATER NOSTER LAKES

(landform by glacial erosion)

Back 70

bedrock depressions created by plucking *when they're filled with water!*

Front 71

CIRQUE

(landform by glacial erosion)

Back 71

bowl-shaped depression @ head of the glacial valley

-the focal pt of growth bc where snow accumulation & ice formation occurs
-begin as irregularities in mountainside & enlarged by frost wedging and plucking
-often occupied by a tarn

Front 72

TARN

(landform by glacial erosion)

Back 72

-small lake
-often occupies cirques

Front 73

FIORDS

(landform by glacial erosion)

Back 73

-deep
-steep sided
-inlets of sea
-@ high latitues
--where mtns adjacent to oceans
-DROWNED GLACIAL TROUGHS
--result of sea level rising after ice age

-depths can exceed 1000 M

Front 74

ARETES

(landform by glacial erosion)

Back 74

-sharp edged ridges
-carved by valley glaciers
-cirques exist on opp sides of a divide
-->as cirques grow the divide reduced to a narrow knifelike structure

Front 75

HORNS

(landform by glacial erosion)

Back 75

-pyramid like peaks
-carved by valley glaciers
-produced by groups of cirques enlarging and converging, producing an isolated horn

Front 76

Glacial Drift

Back 76

term for all sediments of glacial origin
-glacial deposits consist primarily of mechanically weathered rock (with little / no mechanical weathering)

2 types:
1)TILL
2)STRATIFIED DRIFT

Front 77

TILL

(glacial drift)

Back 77

material deposited directly by ice

-typically unstratified & unsorted!

*landforms made by till::
-moraines
-drumlins

Front 78

STRATIFIED DRIFT

(glacial drift)

Back 78

sidiments laid down by glaical meltwater

Front 79

Glacial erratics

Back 79

boulders found in till

-know they've been transported bc different from bedrock below

Front 80

Moraine

Back 80

layers or ridges made by glacial till

TYPES:
[made by alpine glaciers]
-lateral moraine
-medial moraine
[other types]
-end moraine (terminal or recessional)
-ground moraine

Front 81

lateral moraine

Back 81

ridges of till paralleling sides of the valley
-made by alpine glaciers

-ice erodes sides of valley & debris is collected on edges of moving glacier
-ice melts & debris is dropped next to valley walls

Front 82

medial moraines

Back 82

dark stipes of till within ice stream
-created by alpine glaciers

-when two alpine glaciers coalesce to form single ice stream
--till once on sides of each glacier joins to form single dark stripe of debris within newly enlarged glacier

*proof that glacial ice moves

Front 83

End Moraine

Back 83

ridge of till that formed at terminal end of glacier

-deposited when there is equilibrium between ablation & accumulation
-->ice is melting at end but ice flow continually deposits more sediments

TYPES:
1)terminal moraine
2) recessional moraine

Front 84

terminal moraine

Back 84

-type of end moraine

-marks the limit of glacial advance

Front 85

recessional moraine

Back 85

-type of end moraine

-end moraines that were created as the ice front OCCAIONALLY stabilized during retreat
(ablation & accumulation were balanced in different places along retreat)

*difference between terminal moraine & recessional morain = relative positions*

Front 86

DRUMLINS

Back 86

smooth elongated parallel hills
-COMPOSED OF TILL

-steep side faces direction ice advanced FROM
-gentler slope points in direction ICE MOVED

-occur in clusters (drumlin fields)

Front 87

4 major stages in ice age

Back 87

1) Nebraskan

2) Kansan

3) Illinoian

4) Wisconsinan

Front 88

ICE AGE

Back 88

ice covered ~30% of earth's land area

-had 20 glacial/interglacial cycles (occuring every 100,000 yrs)

-most major glacial stages occured during
PLEISTOCENE EPOCH

-began 2-3 ma ago

Front 89

ice sheets

Back 89

exist at much larger scales
-low solar radiation @ poles make them possible

-2 @ PRESENT:
1) GREENLAND ICE SHEET [N pole]
2)ANTARTICA ICE SHEET [S pole]

-aka continental ice sheets

-ice flows out in all directions from a snow accumulation center

Front 90

how much of world's H2o is in glaciers?

Back 90

~ 2 %

Front 91

the antartic ice sheet
(#'s)

Back 91

80% world's ice
65% of earth's freshwater

if melted, sea level rise 60 - 70 M

Front 92

indirect effects of ice age

Back 92

-as ice advances & retreats animals/plants forced to migrate
-change courses of rivers
-upward rebound of crust
(raising after the downwarping {curstal subsidence} from heavy ice)
-->up and in now rather than down & out

-during ice age sea level ~ 100 M lower than today
-climatic changes (ice age = response to significant climate changes)
-during pleistocene epoch = "wetter climate" creating pluvial lakes

Front 93

any successful theory of glaciation has to account for

Back 93

-cause for onset of glacial conditions
-cause of glacial/interglacial periods during pleistocene epoch

Front 94

tillite

Back 94

deposits indicating earlier glaciations (prior to ice age)

Front 95

PLATE TECTONICS

as a cause for glaciation

Back 95

-supercontinent was located at latitudes far south of present positions
-(OR, earlier) ice ages occured when continents in tropical latitudes were carried toward poles

-most commonly accepted


-changes in ocean circulation altered heat/moisture (& in turn CLIMATE)

*ALL OCCUR OVER VAST SPANS OF TIME - SCALE OF MILLIONS OF YEARS*

->*DOES NOT EXPLAIN ALTERNATING GLACIAL/INTERGLACIAL PERIODS*

Front 96

MILANKOVITCH HYPOTHESIS

as a cause for glatiation

Back 96

-variations of incoming solar radiation due to variations in earth's orbit

1)ECCENTRICITY
-variations in shape of orbit around sun
2)OBLIQUITY
-changes in angle of axis
3)PRECESSION
-wobbling of earth's axis

-->can lead to milder winters & cooler summers

*Explains glacial/interglacial periods (on scale of thousands of yrs not millions)*

***accounts for changes in climate over past 300,000 yrs

--called milankovitch cycles

Front 97

eccentricity

Back 97

the shape of earth's orbit around sun

Front 98

obliquity

Back 98

change in angle of earth's axis

Front 99

precession

Back 99

wobbling of earth's axis

Front 100

structural geology

Back 100

studies architecture of crust & processes responsible for deforming it

Front 101

rock structures contain

Back 101

oil fields

ore deposits

Front 102

deformation

Back 102

all changes in size shape orientation and position of a rock mass

-most deformities occur along plate margins

-occurs from tectonic forces

-includes:
1)STRESS
2)STRAIN

Front 103

Stress

Back 103

force / area

(measure of how concentrated the force is)

Front 104

differential stress

Back 104

stress applied unequally in different directions

INCLUDES:
1)compressional stress
2)tensional stress
3)shear stress

Front 105

compressional stress

Back 105

differential stress that shortens a rock body
-plate collisions
-shortens & thickens crust by folding / flowing / faulting

Front 106

Tensional stress

Back 106

differential stress elongates or pulls apart rock unit
-plates are rifted - divergent plate boundaries
-lenthens rock bodies

Front 107

shear stress

Back 107

-often occurs on closely spaced parallel surfaces of weakness (bedding planes)

-similar to slipage between playing cards

Front 108

strain

Back 108

changes in shape or size of rock body from stress

Front 109

how rocks deform

Back 109

rocks subjected to stresses greater than their own strength

deform BY:
1)fracturing
2)folding
3)flowing

Front 110

steps of rock deformation

Back 110

1)first deform elastically
-elastic deformation
(recoverable)
2)after elastic limit surpassed it either FLOWS (ductle deformation) or FRACTURES (brittle deformation)

Front 111

elastic deformation

Back 111

rock will return to original size / shape when stress is removed

*earthquakes release elastic energy*

Front 112

ductile deformation

Back 112

rock flows after elastic limit surpassed

Front 113

brittle deformation

Back 113

rock fractures after elastic limit surpassed

Front 114

factors influencing how rock strength & thus deformation

Back 114

1)temperature

2)confining pressure

3) rock type [rheology]

4)availability of fluids

5)time [strain rate]

Front 115

temperature and confining pressure
affecting rock deformation

Back 115

low temp & low pressure:
Brittle Deformation
[fractures]

high temp & high pressure:
Ductile Deformation
[flows]
clays

Front 116

rock type
affecting rock deformation

Back 116

crystalline rocks composed of minerals = brittle fracture

weakly cemented sedimentary rocks & meta rocks w. zones of weakness = ductile flow

Front 117

"rock structures"
term

Back 117

deformations from mountains to fractures

(the largest folds to the smallest fractures)

Front 118

when studying a region geologists:

Back 118

identify & describe the dominant rock structure

-aided by aerial photography, satellite imagery, digital topography, global positioning systems (GPS)

Front 119

used to decribe orientation of rock layer

Back 119

1)STRIKE (trend)

2)DIP (inclination)

by knowing strike & dip geologists can predict nature, structure & faults of the rock unit

Front 120

strike

Back 120

compass direction of the line of intersection of inclined rock layer or fault with horizontal plane

-expressed as angle relative to N (N10*E ->strike is 10* E of N)

Front 121

dip

Back 121

angle of inclination of the rock compared to horizontal plane

includes angle of inclination and direction rock is inclined toward

Front 122

folds

Back 122

rocks bent into series of wavelike undulations
(during mtn building especially)

-microscopic to hundreds of meters

-result from COMPRESSIONAL stresses
-->the shortening and thickening of crust

PARTS:
limbs
axis
axial plane

Front 123

limbs

(part of fold)

Back 123

refers to the two sides of a fold

Front 124

AXIS
(book calls hinge)

(part of fold)

Back 124

where fold is divided along max curvature pt
--just a line

(like dividing into symmetrical sides)

Front 125

Axial Plane

(part of fold)

Back 125

imaginary surface dividing fold in half
--PLANE dividing into "symmetrical sides" of fold

Front 126

ANTICLINE

type of fold

Back 126

upward / arched rock layers

(the limb of an anticline can also be the limb of a syncline)

Front 127

SYNCLINE

type of fold

Back 127

downfolds / troughs of rock layers

Front 128

basic folds can be :

Back 128

-symmetrical
-asymmetrical
-overturned (type of asymmetrical)

Front 129

symmetrical folds

Back 129

limbs are mirror images of eachother

Front 130

asymmetrical folds
&
overturned folds

Back 130

asymmetrical folds:
limbs are NOT mirror images

overturned folds:
in asymmetrical folds when one limb is tilted beyond the vertical
(can go so far as to lay on its side ->axis would be horizontal)

Front 131

Plunging of folds

(and how anticline & sincline plunge)

Back 131

folds plunge when their axis penetrates the ground

anticlines point IN the direction they're plunging

sinclines point the OPPOSITE direction they're plunging

*plunging = from hitting surface down*

Front 132

Monocline

(type of fold)

Back 132

large, step like folds in otherwise horizontal strata

-ONLY ONE INCLINED LIMB (the other horizontal)

-result from movement along buried faults

Front 133

DOME

(type of fold)

Back 133

upward displacement of rocks
-circular, elongated structure
**LOOKS LIKE A BALD HEAD**

-OLDEST rocks in CENTER, youngest rocks at edge

-can be formed by magma intrusion

Front 134

BASIN

(type of fold)

Back 134

downward displacement of rock
-circular, elongated structure
**LOOKS LIKE A BOWL**

-YOUNGEST rocks in CENTER,
oldest at edges

Front 135

faults

Back 135

fractures in rock allowing displacement to occur

-sudden movements along faults cause most earthquakes

Front 136

dip-slip fault

Back 136

faults in which movement is parallel to dip (inclination) of fault surface
-can produce fault scarps
-parts = hanging wall & footwall

Front 137

fault scarp

Back 137

long low cliffs produced by vertical displacement along dip slip fault

Front 138

hanging wall
v
footwall

Back 138

HANGING WALL:
rock surface above fault
(where miners hung their lamps)

FOOTWALL:
rock surface below fault
(miners foot was)

Front 139

2 Types of Dip-Slip faults

Back 139

1) Normal Fault

2)Reverse Faults

Front 140

Normal Fault

[type of dipslip fault]

Back 140

when hanging wall moves DOWN relative to foot wall
-accomodates extension of crust
-large scale normal faults = associated w/ "fault-block mtns"

Front 141

Fault Block Moutains

Back 141

large scale normal faults

-extend for tens of KMs

Front 142

Horsts

Back 142

alternating uplifted fault blocks
from movement along fault

-create elevated ranges

Front 143

Grabens

Back 143

down dropped blocks from movement along fault

-FORM BASINS

[half grabens = tilted fault blocks]

Front 144

Reverse & Thrust Faults

Back 144

hanging wall moves up relative to footwall
-accomodate shortening of crust
-result from COMPRESSIONAL forces

*reverse faults = dips greater than 45*
thrust faults = dips less than 45*

Front 145

STRIKE SLIP FAULTS

{as opposed to dip slip}

Back 145

displacement is horizontal and parallel to strike of fault

2 types:
1)RIGHT LATERAL:
as you face the fault the block on the opposite side moves right

2)LEFT LATERAL:
as you face the fault the block on the opposite side moves left

Front 146

Transform Fault

Back 146

Types of strike slip fault

-cuts through the lithosphere and accommodates motion between 2 large crustal plates

-many cut thru oceanic lithosphere & link spreading ocean ridges

*EX. SAN ANDRES

Front 147

SAN ANDRES

example of

Back 147

major transform fault

(a large strike slip fault cutting thru lithosphere)

Front 148

hydrologic cycle

Back 148

-endless cycle
-constantly movement
-powered by energy from the sun (provides link between oceans & continents)
-winds transport moisture filled air
-water falls in ocean = completed cycle
-water falls on land = must make its way back to ocean

*BALANCED*
(ie total water vapor in atmosphere remains the same)

Front 149

infiltration

Back 149

the portion of water that soaks into the ground

move downward then laterally (into streams oceans etc)

Front 150

runoff

Back 150

the water that flows over the surface into bodies of h2o ... when rate of rainfall greater than land's ability to absorb it

Front 151

evapotranspiration

Back 151

combined effect of transpiration & evaporation

[transpiration = water released by plants into atmosphere]

Front 152

earth's allocation of h2o

Back 152

oceans: 97 %

glaciers: 2 %

groundwater: .6 %

lakes/rivers, atmosphere: ~.02 %

Front 153

most important erosional agent?

Back 153

RUNNING H2O

Front 154

sheet flow

Back 154

broad thin sheets of h2o across ground

*depends on infiltration capacity of soil*

runoff begins as sheet flow

Front 155

infiltration rate

Back 155

CONTROLLED BY:

1)intensity / duration of rainfall
2)prior wetted condition of soil
3)soil texture
4)slope of land
5)vegetation cover

Front 156

rills

Back 156

tiny channels of current developed from sheet flow

*happens after sheet flow*

-carries water to streams

Front 157

stream's erosional power

Back 157

depends on velocity!

Front 158

velocity of stream

Back 158

depends on :
1)gradient
2)shape / size / roughness of channel
3)discharge

Front 159

gradiant

Back 159

slope of the stream

measured by vertical drop of stream over fixed distance

**the steeper the gradiant the more energy available for streamflow**

**higher gradiant = higher velocity**

Front 160

cross-sectional shape

of stream
affecting velocity

Back 160

determines amount of water in contact w/channel & thus the amt of frictional drag

*most efficient stream = least perimeter for its cross section

*less water in contact = less frictional drag = higher velocity

Front 161

size & roughness of channel

affecting velocty of stream

Back 161

bigger size = lower perimeter:cross section ratio = increases velocity

smooth channel = more uniform flow

irregular channel filled w/ boulders = slows flow

Front 162

discharge

Back 162

amt of water flowing past a certain point at a given time

(cross sectional area)x(velocity)

*normally not constant due to rain & snowmelt

*if discharge increases the stream either increases depth & stays at same rate OR must flow faster*

Front 163

changes from upstream to downstream

Back 163

1)profile
2)velocity increases
3)discharge increases
4)channel size increases
5)gradiant DECREASES
6)channel roughness DECREASES


(width depth and velocity increase due to more water added to stream from groundwater & other sources)

Front 164

profile
(aka longitudinal profile)

Back 164

cross sectional view of a stream from source area (head) to mouth (where river's emptied)

Front 165

base level

Back 165

the lowest elevation to which a stream can erode

*where mout enters body of h2o*

--accounts for fact that streams have low gradients near mouths

2 types:
1)ultimate base level
2)local / temporary base level

*raised base level = deposition
*lower base level = erosion
--->lower base level -->excess energy --> downcuts channel to balance

Front 166

ultimate base level

Back 166

sea level

Front 167

temporary / local base level

Back 167

lakes, resistent layers of rock

limits stream

*when stream enters lake velocity approaches 0 & erosional power is gone

*upstream from resevoir = gradiant reduced, lower velocity, lower transporting ability

*change in local base level = waterfall

*changes river profile

Front 168

changes from upstream to downstream

Back 168

1)profile
2)velocity increases
3)discharge increases
4)channel size increases
5)gradiant DECREASES
6)channel roughness DECREASES


(width depth and velocity increase due to more water added to stream from groundwater & other sources)

Front 169

changes from upstream to downstream

Back 169

1)profile
2)velocity increases
3)discharge increases
4)channel size increases
5)gradiant DECREASES
6)channel roughness DECREASES


(width depth and velocity increase due to more water added to stream from groundwater & other sources)

Front 170

profile
(aka longitudinal profile)

Back 170

cross sectional view of a stream from source area (head) to mouth (where river's emptied)

Front 171

base level

Back 171

the lowest elevation to which a stream can erode

*where mout enters body of h2o*

--accounts for fact that streams have low gradients near mouths

2 types:
1)ultimate base level
2)local / temporary base level

*raised base level = deposition
*lower base level = erosion
--->lower base level -->excess energy --> downcuts channel to balance

Front 172

ultimate base level

Back 172

sea level

Front 173

temporary / local base level

Back 173

lakes, resistent layers of rock

limits stream

*when stream enters lake velocity approaches 0 & erosional power is gone

*upstream from resevoir = gradiant reduced, lower velocity, lower transporting ability

*change in local base level = waterfall

*changes river profile

Front 174

profile
(aka longitudinal profile)

Back 174

cross sectional view of a stream from source area (head) to mouth (where river's emptied)

Front 175

base level

Back 175

the lowest elevation to which a stream can erode

*where mout enters body of h2o*

--accounts for fact that streams have low gradients near mouths

2 types:
1)ultimate base level
2)local / temporary base level

*raised base level = deposition
*lower base level = erosion
--->lower base level -->excess energy --> downcuts channel to balance

Front 176

ultimate base level

Back 176

sea level

Front 177

temporary / local base level

Back 177

lakes, resistent layers of rock

limits stream

*when stream enters lake velocity approaches 0 & erosional power is gone

*upstream from resevoir = gradiant reduced, lower velocity, lower transporting ability

*change in local base level = waterfall

*changes river profile

Front 178

graded stream

Back 178

correct slope & characteristics to maintain velocity to transport material supplied

[not eroding or depositing, just transporting]

->becomes a self regulating system -->EQUILIBRIUM

Front 179

load

Back 179

transported material by stream

1)dissolved load
2)suspended load
3)bed load

Front 180

dissolved load

Back 180

supplied by goundwater

*groundwater dissolves minerals and such from soil

Front 181

suspended load

Back 181

largest part of a stream's load

sediment suspended in h2o

-controlled by velocity and settling velocity (the speed @which particles settle)-larger the particle = more rapid settling)

Front 182

bed load

Back 182

sediment too large to be carried in suspension
-move along bottom of stream

moves by saltation (jump / skip along bed

-in motion intermittantly

Front 183

capacity

Back 183

maximum load of solid particles that a stream can transport

-1/2 controlling load stream can carry

Front 184

competance

Back 184

max particle size a stream transports
-determined by stream velocity

-2/2 controlling load stream can carry

*competence increases as velocity squared (v increases 2 times, competence increases 4 times)

Front 185

deposition

Back 185

caused by decrease in velocity
-competence reduced
-sediment begins to drop out

1)channel deposits
2)floodplain deposits
3)alluvial fans
4)deltas

Front 186

channel deposits

Back 186

1)BARS:
-coarser components (sand gravel)
-temporary

2)BRAIDED STREAMS
-stream deposits material on floor
-accumulate thick enough to choke channel
-force stream to split in multiple paths
--converging & diverging channels threading along bars
*often when load supplied exceepds competency / capacity
*also form when abrupt decrease in gradient or decrease in discharge

3)DELTAS
-forms when stream enters body of h2o
-dying current deposits load of sediments
-delta grows outward -> streams gradient lessens
--channel becomes choked w.sediment & river seeks higher gradient, shorter route
--main channel divides into several smaller ones (distributaries)

Front 187

floodplain deposits

Back 187

[part of valley that gets flooded]

1)NATURAL LEVEES
-form parallel to stream channel by successive floods over many yrs
-when stream overflows it flows over land as broad sheet---decreasing velocity & allowing for load to be deposited

Front 188

Alluvial Fans

Back 188

develop where high gradiant stream leaves a narrow valley
-drop in v causes dumpage of load quickly in cone / fan shaped accumulation

-slopes outward in broad arc


**deposited on land
[deltas deposited in water]

Front 189

3 types of delta beds

Back 189

1)FORESET BEDS
-coarser particles drop out immediately form layers sloping down

2)TOPSET BEDS
-usually covers foreset bed
-deposited during flood stage

3)BOTTOMSET BEDS
-finer silts and clays settling out at a distance from mouth
-horizontal layers

Front 190

stream valleys

Back 190

most common landform on earth

2 types:
1)NARROW VALLEYS
-v shaped
-downcutting toward base level
-can include rapids & waterfalls

2)WIDE VALLEYS
-often include floodplains & meanders

Front 191

floodplains
in wide valleys

Back 191

1)erosional floodplains

2)depositional floodplains

Front 192

meanders
in wide valleys

Back 192

streams that move in sweeping bends

-can produce CUT BANKS
(the zone of erosion outside of a meander)

-when the neck of a meander is narrowed close enough the river can erode thru the narrow neck to the next loop
-->creates new shorter segment [CUTOFF]
---abondoned bend of river = OXBOW LAKE

-can create a point bar

Front 193

point bar

(resulting from a meander)

Back 193

crescent shaped accumulation of sediment deposited inside of meander

Front 194

oxbow lake

(resulting from a meander)

Back 194

the abandoned bend when river assumes the shorter route, cutting off the neck and creating a "cutoff" (the new shorter segment)

Front 195

incised meander

Back 195

meanders in steep, narrow valleys

-caused by drop in base level or uplift of a region

(probably originally developed on floodplain that was near base level -- a change in base level cause downcutting

Front 196

terraces

Back 196

-remnants of former floodplain
-after a river has adjusted to drop in base level by downcutting

Front 197

floods

Back 197

most common & most destructive geologic hazard

caused by natural and anthropogenic factors

Front 198

flood control

Back 198

-artificial levees
-flood control dams
-channelization

Front 199

rivers meander more in:

Back 199

SOFT SEDIMENT

Front 200

How long does it take to remove groundwater resources:

Back 200

TENS of years

(turnover of groundwater is not in our lifetime)

Front 201

are glaciers shrinking?

Back 201

YES bc of global warming

which appears anthropogenic

Front 202

rivers change on what time scale?

river turnover time scale?

Back 202

rivers change in time scale of our lifetime

river turnover takes place in a few weeks

Front 203

problems with flood control?

Back 203

by trying to control floods the frequency is lowered but intensity is increased when one finally does occur

Front 204

what % of earth's freshwater is groundwater?

Back 204

0.6 %

Front 205

measure of amt of water that can be stored by rock / sediment

Back 205

porosity

Front 206

currently glaciers cover __% of earth's land area

Back 206

10 %

Front 207

during last major ice age advance sea level:

Back 207

was 100 m lower

Front 208

broad deposit of stratified drift thats deposited beyond the end moraine of an ice sheet is:

Back 208

Outwash Plane

Front 209

what fault displaces older strata over younger strata?

Back 209

THRUST FAULTS

Front 210

gentle rainfall favors

(infiltration or runoff?)

Back 210

infiltration

Front 211

surface lacking vegetation favors?

(infiltration or runoff??)

Back 211

runoff

Front 212

what caused the formation of yosemite and the great lakes?

Back 212

GLACIERS