Geology Mid Term 3

aerated zone

layer that contains both water and air; above the saturated zone

fracture zone

major line of weakness in earths crust that crosses the mid oceanic ridges at approximately right angle

incised meander

meandering channel that flows in a steep, narrow valley. They form either when an area is uplifted or when base level drops.

mantle plume

narrow column of hot mantle rock that rises and spreads radially outward

bed load

sand, pebbles, and boulders that are moved along the bed of a stream and that are too heavy to be carried in suspension

permeablity

the ability of rock or soil to allow water to flow through it

drainage basin

the area from which a single stream or river and its tributaries drains all of the water

cut bank

the area of active erosion on the outside of a meander, outside of a bend where water moves rapidly

drainage pattern

the arrangement of the streams as seen from above

what is the water table? how does the water table very with the topography of the land?

the level below which the ground is saturated with water.

What features are found in each stage? What type of gradient? What energy level? What size sediments are deposited in each stage?

youthful- high gradient, high energy, gravel sized sediment, vertical erosion, V shaped valleys. Mature- Medium Gradient, Medium Energy, Sand sized sediment, Lateral erosion , begins to form meadows Old- Low Gradient, Low Energy, Silt sized sediment, Lateral erosion

ground water

Water that fills the cracks and spaces in underground soil and rock layers

How does the shape of a river channel affect the flow of a river?

Wide and shallow channels will slow the stream velocity because the area has more surface for the moving water to drag against.

Three stages of river evolution?

Youthfull, Mature, and Old

what is an aquifer? Aquitard?

a body of permeable rock that can contain or transmit groundwater.

distributary

a branch of a river that flows away from the main stream and does not rejoin it

meander cutoff

a channel segment cutting across the narrow neck of a large meander; shortcuts the stream's former course around the meander and locally steepens its gradient or slope

atoll

a circular reef surrounding a deeper lagoon

sinkhole

a closed depression found on land surfaces underlain by limestone

oxbow lake

a crescent-shaped lake (often temporary) that is formed when a meander of a river is cut off from the main channel

cone of depression

a depression of the water table formed around a well when the water is pumps out; it is shapes like an inverted cone

saturated zone

a layer of permeable rock or soil in which the cracks and pores are totally filled with water

unconfined aquifer

a partially filled aquiifer exposed to the land surface and marked by a rising and falling water table

spring

a place where water flow out of rock onto the land surface

fringing reef

a reef attached directly to shore

barrier reef

a reef separated from the shoreline by deeper water of a lagoon

continental slope

a relatively steep slope extending from a depth of 100 to 200 meters at the edge of a continent shelf sown to oceanic depths

divide

a ridge of land that separates two adjacent river systems

bar

a ridge of sediment, usually sand and gravel, deposited in the middle or along the banks of a stream.

what are river bars? braided streams?

a ridge of sediments, usually sand and gravel, deposited in the middle or along the banks of a stream Braided streams occur in rivers with high slope and/or large sediment load.

karst topography

an area with many sinkholes and a cave system beneath the land surface and usually lacking a surface stream

mid ocean ridge

an undersea mountain chain where new ocean floor is produced; a divergent plate boundary

point bar

deposit of sediment build up by a river on the inside bend of a meander

how does the amount of groundwater on earth compare to other fresh water sources?

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what is karst topograpghy?

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Where across a river channel does water flow fastest?

The Middle

porosity

The percentage of the total volume of a rock or sediment that consists of open spaces.

What is gradient?

Measurement of Slope: Rise/Run

River Basin? River divide?

The portion of land drained by a river and its tributaries., any elevation that separates river systems

traction

Movement by rolling, sliding, or dragging

what is the unsaturated zone?

The unsaturated zone is the portion of the subsurface above the groundwater table. The soil and rock in this zone contains air as well as water in its pores.

in what conditions do braided streams form?

heavily loaded streams with sediments and has banks that are easily eroded

stalactite

icicle like pendant of drip stone formed on cave ceilings

recharge

new water that enters the aquifer from the surface

stream terrace

these develop when a stream erodes into the deposits of floodplains formed when streams were formed at higher levels

dentritic pattern

tree-like appearance indilates the rock is equally resistant to erosion and the slope is slight

rectangular pattern

a drainage pattern characterized by numerous right-angle bends that develop on jointed or fractured bedrock

what are alluvial fans?

a fan-shaped mass of alluvium deposited as the flow of a river decreases in velocity.

active margin

a margin consisting of a continental shelf, a continental slope and an oceanic trench

passive margin

a margin that includes a continental shelf, continental slope and rise that generally extends down into a abyssal plane

ocean trenches

a narrow deep trough parallel to the edge of a continent or an island

abyssal plane

a smooth, nearly flat region of the deep ocean floor

continental shelf

a submarine platform at the edge of a continent inclined very gently seaward generally at an angle less than 1 degree

yazoo tributaries

a tributary that flows parallel to the main stream because a natural levee is present

continental rise

a wedge of sediments that extend from the lower part of the continental slope to the deep sea floor

saltation

(geology) the leaping movement of sand or soil particles as they are transported in a fluid medium over an uneven surface

natural levee

- a curvy-linear mound of sand and gravel that parallels the river bank.

How does the position of a river channel/delta change/migrate over time? Give an example?

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comment on rates of groundwater flow? (velocity through what rock types?)

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how do fringing reefs develope into atolls?

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how does a changing water level affect active around a well?

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how does urbanization affect runoff/flooding?

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what are examples of high/low porosity/permeabilty?

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what are some examples f ground waters affect topography?

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what are some strategies/structures for controlling floods?

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what happens locally to the water table around a well?

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what is a spring? what are some features seen when water tables intersect the round surface?

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what is confined aquifer? unconfined? artesian aquifer?

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what is the diferenece between active and passive marigins?

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Braided streams

..., An interwoven stream channel caused by accumulated sediments choking off the channel and the stream splitting into several smaller streams. Occurs when the load supplied to a stream exceeds capacity

What are natural levees? How does river energy change?

..., Banks of stream channel(or margins of a mass wasting flow channel) raised by deposition from flood(or flow)deposits: artificial levees are built along stream banks for flood control.

What are tributaries?

..., Streams and smaller rivers that feed into a main river are called tributaries.

Floodplain? How do they relate to river stages

..., river hitting ocean, slower flow, warmer temp, deeper wider waters

aquifer

A body of rock or sediment that stores groundwater and allows the flow of groundwater

aquiclude

A body of rock that will absorb water slowly, but will not transmit it fast enough to supply a well.

stalagmite

A cone-shaped calcite deposit that builds up from the floor of a cave, generally directly below stalactite

radial pattern

A drainage pattern in which streams diverge outward like spokes of a wheel.

guyot

A flat-topped seamount

delta

A landform made of sediment that is deposited where a river flows into an ocean or lake

meander

A loop like bend in the course of a river

flood plain

A nearly flat area along the course of a stream or river that is naturally subject to flooding

tributary

A stream or river that flows into a larger river

braided stream

A stream or river that is composed of multiple channels that divide and rejoin around sediment bars

trellis pattern

A system of streams in which nearly parallel tributaries occupy valleys cut in folded strata.

artesian well

A well in which water rises because of pressure within the aquifer

alluvial fan

A wide, sloping deposit of sediment formed where a stream leaves a mountain range

base level

Lowest elevation to which the stream can erode downward, for many streams, the water surface level of the body of water into which they flow

What are meanders? Point bars? Cut banks? Oxbow lakes? How do they change over time?

Meanders are a winding, looping curve in the course of a river on soft, flat flood plain. Point bars consists of sediment deposited on the insides of meanders, build out the banks in those parts of the channel. Cut banks form at outer edge of meanders and experience erosion. Oxbow lakes are formerly part of the channel of a meandering stream.

discharge

An outflow of water from a stream, pipe, groundwater aquifer, or watershed; the opposite of recharge.

Deltas? Tributaries

Deltas are an accumulation of sediment formed where a stream enters a lake or ocean. Tributaries are a river channel branching out from the main river and not rejoining it.

What are some examples of stream drainage patterns? What landscape/bedrock/ structures influence each drainage pattern?

Dendritic- Uniform rock, Rectangular- Regular joined rocks, Radial - forms on conical mountains Trellis- erosion on folded sedimentary rock

stream gradient

Downhill slope of a stream's bed or the water surface, if the stream is very large.

What are three general styles of river erosion?

Hydraulic Action, Abrasion, and Solution

what is porosity? Permeability?

Porosity is the percentage of void space in a rock. It is defined as the ratio of the volume of the voids or pore space divided by the total volume. the state or quality of a material or membrane that causes it to allow liquids or gases to pass through it.

How do dams affect river processes? What are some functions of dams?

Reduce dangers of flood water and sedimentation . Can trap water and release it slowly and catches sediment.

hydrologic cycle

The cycle through which water in the hydrosphere moves; includes such processes as evaporation, precipitation, and surface and groundwater runoff

Why does the Mississippi River delta have the shape (birdfoot delta) that it does?

The delta has a long history of flooding; any more flooding will have disastrous effects.

what is the hydrologic cycle? how so rivers/ stream and groundwater fit into hydrologic cycle?

The hydrologic cycle is the flow of water through ecosystems, to the atmosphere, and back to ecosystems. Because water carries dissolved and particulate matter, the hydrologic cycle connects ecosystems to each other. plants return water to the atmosphere by transpiration.

dissolved load

The load contains dissolved materials such as sodium and calcium.

suspended load

The load contains small rocks and soil in suspension, which can make the river look muddy.

shelf break

The section of the continental shelf where the slope abruptly becomes steeper, usually at 120 m to 200 m

water table

The upper level of the saturated zone of groundwater

What are back swamps? Yazoo Tributaries? How do they relate to natural levies?

Back Swamps are swampy depressed area of a floodplain between the natural levees and the edge of the floodplain. A yazoo tributary is a small tributary channel that is prevented from joining the main stream channel by the presence of levees.

What is base level?

Base level is the lowest elevation to which a land surface can be eroded by a stream. A drop in base level pushes a river system toward degradation, while a rise in base level pushes the system toward aggradation.

What are ways (three) that rivers carry material down stream? Discuss how each process works.

Bed Load- Large or heavy sediment particles that travel on the streamed Suspended Load- Sediment that is light enough to remain lifted indefinitely Dissolved Load- Soluble products of chemical weathering