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ground water and glaciers


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Porosity increases as...
grain size decreases
Porosity is greater in...
clay-sized sediment than in sand
Porosity pore spaces are
larger in sand than in clay sized sediment
Permability increases as...
grain size increases
Permability is greater in...
sand than in clay sized sediment
In permability, pore spaces
"communicate" better
Ground water moves in response to differences in...
pressure and elevation
Ground water velocity is influnced by
- Slope of water table
- Permability
- % of rock or sediment that is open
- ability to hold water
- ability to transmit water
Perched water table
isolated above the regional water table
Vadose zone =
unsaturated zone above the water table
Water table =
- ground water in the saturated zone
- upper surface of saturated zone ...two dimensional
Capillary fringe =
3D zone between saturated and unsaturated zones
Pollutants of ground water
- pesticides and herbicides
- fertilizers
- heavy metals
- bacteria, viruses, parasites
- acid mine drainage
- radioactive waste
- gasoline
- natural pollution
Over pumping ground water can result in:
- Falling water table
- Ground subsidence
- Saltwater intrusion
Artificial recharge may meet with...
only limited success
surface expression of the water table
Gaining stream
stream gains from ground water
Losing stream
stream is loosing to ground water zone
surface collapses
solution valleys
- limestone removal at the surface
- valley-like depressions formed by a linear series
Void spaces below ground
- Dripstone
- Flowstone
- stalactite
- stalagmite
early karst stage development
- small caves filled with water
- large lakes
- springs
- streams common
- water table near land surface
middle karst stage development
- large caves filled with water in basal portions
- small lakes
- few streams
- sinkholes
- thin cave roofs
late stage karst development
- very large caves only partly filled with water
- disappearing streams
- sinkholes
- thin cave roofs
- water table well below land surface
hot water underground
- hot springs
- geysers
- precipitation of dissolved ions
- mud pots
- geothermal energy
Hot springs
- near magma or cooling igneous rocks
- deep-circulating groundwater
Precipitation of dissolved ions
-Travertine- calcite
- Sinter- silica
structures that penetrate water - bearing zone within the saturated zone
Water table may _____ seasonally in wells
rise or fall
recharge =
discharge or production =
may fall
cone of depression
occurs due to excessive production
the depressed water level at the production well
artesian well
a well from a water-bearing zone
(confined pressure)
recharge always has a
higher elevation
Potentiometric surface
the surface area water will rise to in the absence of friction
under pressure =
confined above and below
- confining beds above the water-bearing zone
- usually > 3' thick
Effects of ground-water action
- chemical weathering
- can reduce whole regions of the earth's surface
- karst topography
chemical weathering
-Slighty acidic ground water can attack minerals
- Most commonly: Calcite and the rock equivalent = limestone
karst topography
areas underlain by soluble bedrock
- calcite
- halite
other effects of ground-water action
- Preservation of fossils by minerals in groun water solutions (petrified wood)
- sedimentary rock cement : calcite and silica
~ concretion
~ geode
water-bearing zones
any sediment or rock unit that allows water to flow through it
any water-bearing zone that will supply sufficient water to a well or a spring
"confining" bed
- usually clay- sized sediment
unconfined water-bearing zone
water table
confined water-bearing zone
trapped between two layers of rock
Ground water
any water filling pore space, cracks, and crevices in rocks or sediment
Accumulation Zone
upper zone of a glacier where snow and ice are collected and compacted and ice is recrystalized. Ice and snow build up faster than it can melt, evaporate, or undergo sublimation

A and C
Ablation Zone
lower zone of a glacier where shrinkage takes place. Ice melts, evaporates, or sublimates faster than new ice can form

A and C
snow/ firn line
transition line between the zone of accumulation and zone of ablation

A and C
Bottom end or snout of a glacier

A and C
Bowl-shaped depression on a high mountain slope, formed by a cirque glacier

Steep-sided, pyramid-shaped peak produced by headward erosion of several cirques

Sharp, jagged, knife-edge ridge between 2 cirques or glaciated valleys

any rock basin lake, stream gauges out rocks, create rock dam

Mountain pass formed by the headward erosion of criques

Truncated Spur
Steep sided ridge that divides glacial tributaries and is lopped off at its lower end- see triangular facet

Triangular Facet
clipped off end of truncated spur or arete found after total wastage of a glacier has occurred caused by larger main trunk glacier

Lateral moraine
ridge of till formed from melting ice and mass wasting at the side of a valley glacier

medial moraine
ridge of till either in transit or deposited along the boundary between 2 tributary glaciers that have merged 2 form a larger valley glacier

Recessional End Moraine
Ridge of till that forms at terminus of a glacier, behind (up-glacier) and generally parallel 2 the terminal moraine: formed during a temporary half (stand) in recession of a wasting glacier

A and C
Terminal End Moraine
Ridge of till that forms at the farthest advance of a glacier

A and C
Ground Moraine
Sheet like layer (blanket) of till left on landscape by a receding (wasting) glacier

A and C
Drift- Till
Unsorted deposits laid down directly from a glacial ice melt

A and C
Drift - Outwash
Sediment transported by meltwater from a glacier and deposited in front of (down-sloe from) the terminus of the melting glacier sorted by melt water

A amd C
Faceted Boulder
A kind of erratic or cobble that has/ plained or scoured sides abraided by a glacier

A and C
Boulder or large fragment of rock, resting far from its source on bedrock of a differet type carried there by the glacier

A and C
Rock Flour
Pulverized rock produced by glacial abrasion- silt and clay sized particles- a suspension in melt water

A and C
Unstratified sheets of clayey sily and silty clay transported beyond the margin of a glacier by wind and/ or braided streams; it is compact and able to ressist significant erosion when expressed in steep slopes or cliffs

A and C
Abrasive action by a glacier involving scraping, gouging,

A and C
long, narrow, sinuous ridge of stratified drift deposited by meltwater streams of flowing under glacial ice or in tunnels w/ in the glacial ice.

A and C
ice sheet
a very large, thick mass of glacial ice flowing outward in all directions from one or more accumulation centers. continental glacier- larger than 50 sq. km

Ice cap
A mass of glacial ice covering though not restricted to a high upland or plateau and spreading out radially - smaller than 50 km

A steep sided inlet of the sea formed when a glacial ice trough was partially submerged- drowned u shaped valley

Fracture in an ice body in the rigid or brittle zone- wider at the top, and narrower at the bottom can open and close

A and C
stream lined hill, asymmetrical in lengthwise profile, commonly composed of till, ideally with a steep slope facing the direction from which the ice came, and a gentle slope that points down glacier

Roche mountonnee
Asymmetrical knoll of small hill of bedrock, formed by glacial abrasion of the smooth stross side (side from which the glacier came) and by plucking (prying and pulling by glacial ice) on the less-smooth lee side (down glacier side)

A and C
Glacial striations and grooves
parallel linear scratches and grooves in bedrock surfaces, resulting from glacial scouring

A and C
Outwash plain
Plain formed by blanket- like depostition of outwash; usually an outward braided plain, formed by the coalescence of many braided streams having their orgins along a common glacial terminus

A and C
Steep-sided mound of stratified drift that formed in contact with glacial ice

A and C
small rounded lake or water-saturated depression in glacial drift, formed by melting of an isolated, detached block of ice left behind by a glacier in retreat

A and C
line tht divides the zones

A and C
Snow recrystalizes to form
firn and then glacial ice
Positive budget
Advancing glacier
- Zone of accumulation - increases exceed the
- Zone of wastage- decreases
Negative Budget
Receding Budget
- Zone of acumulation- increases r less than the
- Zone of wastage- decreases
the terminus moves _____ with a positive budget
forward (down)
the terminus _____ with a negative budget
melts back more (recedes, while forward ice flow continues downward/ NEVER STOPS MOVING)
Moving body of ice either from on land or by recrystallization of snow
Evidence of moment from high two low elevations include two types:
- Apline: in mountaint valleys
- Continental: over large continent sized areas
Glaciers develop where
annual snow doesn't melt away in warm seasons which is 2% of the Worlds water budget!
Examples of places glaciers may develop
- Polar regions
- Heavily winter snowfall
- high elevations
- 85 % in antarcticatoday
- 10 % in Greenland
lithified ice deposit

A and C
Rigid zone
the upper zone where ice crystals r locked
-Crevasses may form here

A and C
Plastic (flow) zone
Internal flowage due to friction

A and C
basal sliding
glaciers sliding along its base

A and C
Continental glaciers: Ice sheets move
downward and outward from a central high
Gravity =
driving force
Nivation Basin
Birthplace of a glacier- the beginning of future cirque valleys may start up

A and C
glacial ice is moving, line that divides the fields that join the glacier

Direct effects in North American glaciation
- Scoured much of Canada
- Cut Great Lakes
- Deposited till and flattened midwest
- Exstensive apline glaciation in mountains
Indirect effects of glacial ages
- Pluvial lakes
- Lowering of sea level
- Fjords
- Crustal rebound
evidence for older glaciation
- Tillite
- Precambrian glaciation
evidence for a super continent
late paleozoic glaciation
Wastage of glaciers "Shrinkage"/ ablation
- melting
- evaporation
- sublimation
- calving into icebergs
rock steps
rock basin lakes-tarns
erosion under the ice
A and C
erosion above the ice
perdominatently A
Under the Glacier
- abrasion and plucking
- bedrock polished and striated
- rock "flour" washes out of glacier
-Polishing and rounding
Above the glacier
- frost wedging takes place
- Erosion above glaciers steepens slopes
Erosional lanscapes associated with alpine glaciation

Glacial valleys
- U-shaped valleys
- Hanging valleys
- Truncated spurs - Triangular facet
- Rock- basin lakes/tarn
- Rounded knobs- rouche mountonnees
Causes 4 glacial advances
- Major volcanic activity
- Plate tectonics
- Changes in ocean current circulation
- Milonkovitch - solar cycles
" all we need is an overall decreases in average word temp"
Milonkovitch cycles- solar cyles change climate
- earth's orbit (~100 ky)
- tilt (~41ky)
- Precession (~26ky)
erosional landscapes associated with continental glaciation
-Grooved and sriated bedrock
~large to small rock surface abrasions
-Rounded hills and mountains
examples of outwash
-braided streams
example of a glacial lake
Alpline Glaciers
-in former stream valleys of mountainous areas
-high altitude, high latitude, and/or high precipitation
continental glaciers
-form over a large area, unrestricted by valleys as:
~ Ice sheet: largeor > 50,000 km2
~Ice cap: smaller
Peak of glaciation
- 18,000 yrs ago
- over 30% of the earth's land area was ice covered
- sea level- 200-300 ft lower than today
Theory of glaciation

North America and northern europe heavily glaciated from
-2 million years ago to 10,000 yrs ago
- 4-5 glacial pulses (250,025 years duration each)
Pluvial lakes
Lakes formed during a period of increased rainfall. This occurred in many non glaciated areas during periods of continental...

A and C
braided stream
a stream with multiple dividing and rejoining channels

A and C

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