Nat park exam 2

How does ground water fit into the hydrologic cycle

massive underground reservoir that stores, moves and filters water

Belt of soil moisture

groundwater trapped in soil by molecular attractions

• used by plants and animals

Zone of aeration

sediment and rock that contains water and air in the pores

• pores: space between grains, contains belt of soil moisture

zone of saturation

sediment and rock that contain only water in the pores

• upper limit of this zone

What is water table?

underground boundary between unsaturated soil surface and the saturated zone below

• level based on rain, drought and pumping

• highest under hills, lowest under valleys

Porosity

the total amount (%) of voids and openings between grains in sediment or rock

• how much water can be stores

Permeability

the connectivity of pores in sediment and rock

• how fast the water flows

Aquitard

impermeable layers that hinder flow of ground water

• slow process

• water moves through from pore or pore or through fractures

Aquifers

porous and permeable rock that transmit water freely

• sand and gravel

Darcy’s Law

states how groundwater moved under the influence of elevation difference between the area of recharge and discharge (head)

Hydraulic gradient

slope of the water table

• the greater the gradient, the faster is flows

Everglades Floridan Aquifer

• loose sediment over limestone bedrock

• series of aquifers and aquitards

• water table is shallow or above ground

• flow to south west

• leads to caves and sinkholes

Everglades watershed

flowing from kissimmee river through lake okeechobee down to florida bay

Everglades problems

• 50% decline in wading birds, near extinction of florida panther, invasive species, decreased water quality

• eroded limestone and decaying plant material

• salt water invasion

• fertile soil drying up

Speleothem

any secondary mineral deposit in caves

• calcite or gypsum

flow stone

made by water flowing over a wall

stalagtites

made by water dripping from the cave ceiling

stalagmites

made by water dripping onto the cave floor

cave column

when stalactites and stalagmites grow into each other

helictites

irregular, twisted speleothems cave sediment, flowing water can deposit sediment in a cave

Mammoth Caves Native Americans

• Used caves 3000-4000 years ago

• Evidence: baskets, torches, petroglyphs, mummies

How did Mammoth caves form?

when acidic rainwater dissolves through the Mississippian limestone

• Surface flow water draining into the caves, flow through and exits

• water enters through sinkholes on the surface

How are caves related to ground water

caves are formed and shaped by groundwater

What are sinkholes?

a depression or hole in the ground caused by a collapse of the surface layer

• usually when acidic water dissolves underlying bedrock like limestone, dolomite or gypsum

How are caves formed

chemical dissolution of limestone by acidic water over millions of years

• carbon diozide gets absorbed by the water to make weak carbonic acid

Why are limestone and carbonate platforms important to the origin on caves?

soluble by mildly acidic water

ground water can dissolve the rock over millions of years

What are glaciers?

thick mass of ice that originates on land from the accumulation and compaction of snow

How do glaciers fit into the hydrologic cycle?

long term freshwater reservoirs

How do glaciers flow?

primarily gravity because of their immense weight

• internal deformation and/or basal sliding

Zone of accumulation

zone where snow accumulates and ice is formed

Zone of wastage

zone where more ice is removed than added each year

Firn line/snow line

boundary between accumulation and wastage zones

• glaciers flow in response to a balance between accumulation and wastage

how do glaciers pick up sediment?

• Picking up rock at the base of mountains (plucking)

• when trapped rocks grind the underlying surface (abrasion)

Alpine (valley) glaciers

relatively small glaciers that exists in the valleys of high mountains

• Alaska, Alps, Himalayas, Pyrenees

Ice Sheets

great accumulations of ice that occur in polar regions

• cover 10% of land today

• Antarctica, Greenland

Ice Shelves

Large, flat extensions of ice sheets that float on oceans

U shaped valleys

wide, u shaped valleys created by alpine glaciers

Fjords

glacial valleys partially filled with sea water

Hanging Valley

valleys cut by smaller tributary glaciers that enter the main valley at a considerable height

Roche moutonnée

elongated hills of bedrock, eroded, scoured, and smoothes by glaciers

Glacier striations

“scrape marks” left on rocks from a glacier

Moraines

elevated ridges of sediment that are deposited at the sides and front of glaciers

End Moraine

Moraine deposited in front of a glacier

Ice sheet landscape

tend to smoothed the landscape by eroding high areas and filling in low areas

Till

unsorted, sediment deposited as glaciers melt

Stratified Drift

sorted and layered sediment deposited by flowing melt water

terminal moraine

outermost end moraine, marks advance of ice

Drumlin

asymmetric hills of till that were smoothed and elongates as ice moved over them

outwash plain

sediment laid down by melt water in front of glacier

kettles

little lakes or ponds on outwash plains

• chunk of ice gets left behind by glacier, water flowed around it and deposited sediment to leave a hole

Eskers

rivers of water under the ice

• has sediment too

erratic boulder

massive boulders transported and deposited by glaciers

Glacier Nat park history

• Montana

• natives lived here for many years

• 1892 tourists came from railroad built

• 1910 nat park established

Glacier nat park sed structures in belt supergroup

• mudcracks, ripples, abundant stromatolites

• mostly shallow marine for layers

Glacier park creatateous depositions

shallow sea flooded N.A.

• thick shale deposits

• mountain building in late cretacaous

ooids

small spheres of calcite, indicates shallow tropical marine water

Igneous sill

layer of unsolidified lava that was injected into the Helena Formation

Sheppard formation

glacier park, limestone and siltstone with mud cracks and ripples

lewis thrust

the rocks of the belt supergroup pushed over the cretaceous rocks

Glacier park sculpting

alpine glaciers in the last 2 my created most features in the park

• gradual retreat over last 10k years

Ice ages

periods of time in which glaciers and ice sheets are more widespread than today

two causes of glaciations

plate tectonics: large landmasses at poles, large continents

orbital controls: variation of heat from sun, Milankovitch cycles

Carlsbad formation difference

the cavers were formed through sulfuric acid dissolutions, rather than typical carbonic acid

How is Carlsbad cave related to surface flow?

modern day seepage of rain and snow melt that drips into the cave

• helps form stalactite and stalagmites

How was Yosemite valley found?

• Natives in the area for millennium

• gold rush and military conflicts led to settlers coming over

what are batholiths?

massive underground bodies of igneous rock formed by cooled magma

How are batholiths related to yosemite

• major uplift and erosion in last 65 my

• up to 6 km of rock eroded and batholiths were exposed

What did ice do in yosemite

• glaciers form in valley 70k years ago

• recede in last 10k years

• some small mountain glaciers left

• shaped features like half dome, yosemite valley and el capitan

Who were the first people in Acadia

• red pain people several thousand years ago

• other natives later

• Portuguese find shoreline in 1529

• french find this too and begin to trade

Acadia geological terrane

• Avalonia terrane

Acadian orogeny shaped the park

• second of three orogenies that made Appalachians

• N.A. collided with Avalonia

• sed rocks were metamorphosed and intruded by granite

How did waves and ice sculpt acadia

• shaped by continental glaciation of igneous and metamorphic rock

• waves modify the shoreline

what glacial features are preserved in acadia

maine rising since the ice lifted, since there is less weight

• glacial erratics and till

• cadillac mounted (rounded)