GSP 150 Stan Test 4

oxbow

a meander that is cutoff

potholes

abrasion by stones on bedrock riverbed creating deep depressions

perched water table

accumulation of water suspended/perched above the main water table by an aquiclude

floodplains

area on either side of stream where the water overflows its banks

drainage patterns

because of friction, the water close to the bank & bed moves slower & the water in the upper-middle moves faster

regolith

bedrock that has been broken apart into a surface layer of unconsolidated rock particles

lake

body of standing water within continental margins enclosed on all sides by land which receives water from streams, overland flow & ground water

saturated zone

bottom zone of subsurface water where all pores & spaces are filled with water

drainage divide

boundary, usually the top of a slope, that feeds a drainage basin

exfoliation

caused by erosion of overlying crust, reducing pressure on the rock beneath causing it to crack in parallel layers to the surface

degradation

causes meandering when sediment loads are reduced

stream flow

channelized surface water runoff

carbonation

chemical weathering caused by carbon dioxide dissolving in water, forming carbonic acid, which dissolves minerals in rock that are then washed away

oxidation

chemical weathering caused by reactions with oxygen & water

hydrolysis

chemical weathering caused by reactions with water

accelerated erosion

clearing of vegetaion by rain splash, leading to reduced infiltration, reduced flow resistance & reduced root support

abrasion

collision of transported rock fragments into bedrock channel walls & floors

alluvial fans

common in arid landscapes, deposits of sediment from streams flowing down a narrow canyon or gorge onto a plain

types of mass wasting

creep (slow, dry); fall (fast, dry); landslide (fast, wetter); flow (slow-fast, wet)

drawdown

curving the water table down around the sides of a well in a cone of depression

cut banks

degradation from alluvium being removed by fast moving outer edges of streams

lag time

delay in the response in stream discharge due to heavy rainfall/snowmelt

alluvium

deposit of sediment which is carried by water- the term _____ is used to describe any stream-laid sediment deposit

point bars

deposition of alluvium on inner banks of meandor

travertine

deposition of carbonate matter on exposed rock in caverns caused by a drop in the water table

playa

desert basins that are dried out from evaporation, leaving behind silt, clay and salt

corrosion

dissolution of rock

cone of depression

drawdown of the water table caused by a well- the area around the sides of the well that are left dry

rockfall

falling, bouncing & rolling rocks down a steep slope

hydraulic action

force of water on alluvium materials

stalagmite

formed by carbonate matter hitting a cavern floor & rising up (g- ground)

braided streams

formed by excess material deposited as alluvial valley fill (often near glaciers)

terraces

formed by removal of alluvial valley fill, causing a meandering stream

sinkholes

formed when caverns created by chemical weathering of limestone collapse

entrenched meanders

formed when rapid uplift causes meandering rivers to cut deeply into the underlying bedrock

joints

fractures in bedrock caused by tectonic forces, which often occur in parallel and intersecting planes

downcutting

gorge formed from stream flowing through uplifted land in stage 2 of gradation

artesian well

ground water under pressure & flowing freely because an aquifer is between 2 aquicludes & the wells elevation is below the level of the upper aquiclude

biological action

growth of plant roots which wedge joint blocks apart

stalactite

hanging accumulation formed by carbonate matter dripping from the ceiling of a cavern (c- ceiling)

natural levee

hills of earth deposited near a stream caused by water going over the banks of the stream and dumping its sediment

frost action

in cold climates- repeated (freeze/thaw) growth & melting of ice crystals in joints & pores which often forms fields of rock rubble as in the Arctic island

salt crystal growth

in dry climates- slow evaporation of ground water from outcropping sandstone which breaks rocks apart grain by grain forming surface pits, niches, shallow caves and rock arches

percolation

infiltrating water in the subsurface layer that moves through the soil-water belt into the groundwater zone

discharge

is a measure of the volume of water per unit of time passing through a cross section of a stream at a given location

badlands

landforms in arid environments with high rates of slope erosion from wind & water

plateau

large, flat, cliff ringed landforms surrounded by lowland plains, often made of a sandstone top layer with a layer of shale underneath

aquifer

layer of rock or sediment that contains abundant freely flowing ground water often made up of sand/sandstone

aquiclude

layer of rock that is relatively impermeable & holds little free flowing water often made up of clay/shale

talus

loose, fallen rock accumulations at the bottom of cliffs & steep slopes which are often cone shaped

rotational landslide

mass rotates as it slides downslope leaving no gap behind

translational landslide

mass slides directly downslope, often on top of an impermeable layer, leaving a distinct displacement or gap

soil creep

mass wasting by very slow, downhill movement of regolith & soil

solifluction

mass wasting caused by saturation of soil which is common in tropics & Arctic

lahar

mass wasting flow on slopes of erupting volcanoes

colluvium

material transported downslope because of gravity & accumulated at the slope's base

angle of repose

maximum slope angle at which disaggregated (broken up) earth can stay in place without moving

mesa

medium sized plateau

unsaturated zone

middle zone of subsurface water which still has air pockets where water percolates down

earthflows

moderately rapid movement of water saturated regolith & soil which has a source area, main track & deposition area

back swamp

mucky, marshy area in a flood plain, between a levee and a bluff

debri flow

mudflow mixed with boulders

drainage basin

or watershed- organized surface water runoff made of a branched network of streams & adjacent slopes that feed the streams

fluvial processes

overland flow & stream flow which create landforms by erosion and deposition

hydrographs

plot of stream flow over time at a particular location which shows the relationship between discharge & precipitation

cryosphere

portion of the hydropshere where water is stored as ice

chemical weathering

process of altering minerals that make up rocks through reactions with water, oxygen and acids

physical weathering

process of breaking down bedrock into regolith, without chemical alteration, such as rain, wind, freeze/thaw, salt crystals, plant roots & erosion

mudflows

rapid flow of water saturated mud which pours down slopes & valleys to lower elevations

base flow

regular seepage of ground water into a stream

bed load

rocks being moved along a stream bed

meanders

s-shaped stream formation from alluvial deposition on the inner banks and erosion on the outer banks of the stream

dissolved load

sediment in solution moving down a stream

suspended load

sediment suspended & moving down a stream

stream gradient

slope of stream which affects the velocity- higher slope= higher velocity & narrower channel; lower slope= lower velocity & wider channel

butte

small plateau

bedrock

solid, unaltered rock

thermal action

temperature fluctuations causing minerals to expand (heated) & contract (cooled)

stream capacity

the amount of sediment a stream can carry- higher velocity= higher capacity

pores

tiny space between mineral grains in igneous & metamorphic rock and sediment grains in sedimentary rock

water table

top layer of the saturated zone, which wells must go past to produce water & which is higher under hilltops than valleys and fluctuates during seasons of drought or wet periods

soil water belt

top zone of subsurface water, which is available to plants

ground water flow

water slowly flows along curved paths because of the pressure gradient set up by gravity & the sloped water table

ground water

water that infiltrates, seeping downward and not evapotranspiring creating the saturated zone

joint block separation

weathering of igneous & metamorphic bedrock into blocks at joints

granular disintegration

weathering of sedimentary rock into chunks at pores

cutoffs

when an oxbow erodes through

aggradation

when bed load increases above stream's transport capacity

mass wasting

when earth materials overcome friction & move downslope

gully erosion

when material is removed as rills grow over time creating large, steep-sided trenches

rill erosion

when material is removed in small, closely spaced channels

sheet erosion

when material is removed in thin, uniform layers

infiltration

when precipitation reaches the ground surface & enters the soil, regolith or rock

overland flow

when precipitation reaches the ground surface & water moves downslope as in surface runoff

slope erosion

when unchanneled overland flow moves particles of regolith, sediment or soil (silt-gravel) downslope

Karst terrain

where chemical weathering of limestone is very active causing caverns & sinkholes

streams

where the land sinks below the water table

nickpoints

where water cuts through uplifted land (waterfalls) in stage 1 of graded stream evolution

urbanization impacts

1- decrease in lag time because of increased impervious surfaces (concrete) which decreases ground water flow & increases overland flow 2- storm sewer systems decrease runoff travel time for storm water to reach stream

graded stream evolution

1- stream established, tectonic activity causes uplift & steep nickpoint (waterfall) forms 2- gradation begins- lakes marshes drained or filled, gorge is downcutting & tributary valleys extending 3- gradation in process (progress), floodplain developed, valley widens 4- graded profile attained, floodplain widened to accommodate channel meanders