ground water and glaciers
Terms
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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 - Porosity
-
- % of rock or sediment that is open
- ability to hold water - Permability
-
"Flow"
- 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
- Spring
- surface expression of the water table
- Gaining stream
- stream gains from ground water
- Losing stream
- stream is loosing to ground water zone
- sinkholes
- surface collapses
- solution valleys
-
- limestone removal at the surface
- valley-like depressions formed by a linear series - Caves
-
Void spaces below ground
- Dripstone
- Flowstone - dripstone
-
- 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 - Wells
- structures that penetrate water - bearing zone within the saturated zone
- Water table may _____ seasonally in wells
- rise or fall
- recharge =
- rise
- discharge or production =
- may fall
- cone of depression
- occurs due to excessive production
- drawdown
- 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
- Aquifer
- any water-bearing zone that will supply sufficient water to a well or a spring
- Aquitards
-
"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 - Terminus
-
Bottom end or snout of a glacier
A and C - Cirque
-
Bowl-shaped depression on a high mountain slope, formed by a cirque glacier
A - Horn
-
Steep-sided, pyramid-shaped peak produced by headward erosion of several cirques
A - Arete
-
Sharp, jagged, knife-edge ridge between 2 cirques or glaciated valleys
A - Tarn
-
any rock basin lake, stream gauges out rocks, create rock dam
A - Col
-
Mountain pass formed by the headward erosion of criques
A - Truncated Spur
-
Steep sided ridge that divides glacial tributaries and is lopped off at its lower end- see triangular facet
A - 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
A - Lateral moraine
-
ridge of till formed from melting ice and mass wasting at the side of a valley glacier
A - 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
A - 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 - Erratic
-
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 - Loess
-
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 - Scour
-
Abrasive action by a glacier involving scraping, gouging,
A and C - Eskers
-
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
C - 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
C - Fjord
-
A steep sided inlet of the sea formed when a glacial ice trough was partially submerged- drowned u shaped valley
A - Crevasse
-
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 - Drumlins
-
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
C - 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 - Kames
-
Steep-sided mound of stratified drift that formed in contact with glacial ice
A and C - kettles
-
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 - Firn
-
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)
- Glacier
- 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 - Tillite
-
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 - Bergschrund
-
glacial ice is moving, line that divides the fields that join the glacier
A - 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
-
-stream
-braided streams
-esker
-kames
-kettle - example of a glacial lake
- varve
- 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