Final Test Vocab

Weathering

breakdown of rock material at or near Earth’s surface.

mass wasting

gravity induced downslope movement of rock material that occurs without the assistance of a geomorphic agent. (a rock falling from a cliff) Movement due to gravity alone!

physical weathering

disintegrates rocks breaking larger blocks or outcrops of rock into smaller clasts (mechanical disintegration of rocks)

chemical weathering

decomposes rock by chemical reactions that remove ions from the original rock-forming materials.

thermal expansion and contraction

a physical weathering process where splitting of rock due to expansion/contraction; caused by individual mineral grains in rock breaking free. The cracks allow water to permeate. hot → cold → hot → cold; etc.

granular disintegration

the breaking free of individual mineral grains from a rock

freeze/thaw weathering

a physical weathering process where when water freezes it expands and causes large pressures against walls and bottom and eventually breaks and cracks under this pressure. the breaks are angular and talus piles can develop beneath rock outcrops.

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Usually happens at upper mid and lower high latitudes, high mountains, and tree lines; not sig. at lower latitudes because temp does not drop low enough and with enough frequency.

hydration

A physical weathering process water molecules attach to the crystaline structure of a mineral causing those minerals to expand. (expands when hydrated and shrinks when dehydrated).

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When water evaporates it leaves behind salt crystals that freeze in these cracks and wedge the pieces apart. (salt crystal growth)

oxidation

a form of chemical weathering where the chemical union of oxygen atoms with another substance creates a new product. After this is is generally more chemically stable.

solution

a chemical weathering process where mineral forming ions dissociate and the separated ions are carried away in the water. more acidic water speeds up this process.

carbonation

a chemical weathering process and a type of solution that involves carbon dioxide and water molecules reacting with and decomposing rock material. most effective on carbonate rocks (containing CO3)

hydrolysis

a chemical weathering process where water molecules ALONE react with chemical components of rock-forming minerals thus creating new compounds. It can happen on the subsurface too. Most common minerals effected are silicate.

joint set

multiple joints that are parallel of each other. Two of these can cross each other at an angle. these occur at sites of concentrated weathering (fracture that allows water or wind to move vertically through rock)

spheroidal weathering

distinctive rounded weathering patterns developing off joint sets. Weathering is less susceptible because there are no sharp edges for weathering to attack.

soil

a relatively thin unit of predominantly fine-grained unconsolidated surface material.

earth

A ticker unit of soil of the same type of material

debris

a mass of sediment composed of a wide range of various grain sizes, at least 20% of which is gravel-sized

mud

saturated sediment consisting of mainly clay and silt, which are the smallest particle sizes.

slow mass wasting

Mass wasting that takes place over long periods of time and effects are not quick

fast mass wasting

a mass wasting event that occurs rapidly and can be witnessed by people. The speed of the movement depends on the quantity, composition of material; steepness of the slope; water amount involved, vegetative cover, and triggering factor. Usually leave a upslope scar on the landscape where material had been removed. and deposit where material had moved to.

creep

a slow mass wasting process where particles slowly go to lower elevations. It is widespread and persistent and results from a heaving process.

heaving

individual soil particles are first pushed upward perpendicular to the slope and then eventually fall straight downward due to gravity. It can be caused by freezing and thawing or wetting and drying.

solification

A slow mass wasting event where downslope movement of water saturated soil or regolith. Common where permafrost is present (high latitude/high elevation). Active layer freezes in winter and thaws during summer. This causes water saturated soil mass that sags slowly downslope until refreeze.

rockfall

A fast mass wasting process where rocks fall from steep bedrock cliffs by weathering of the clasts from the rest of the cliff or large rock mass that fall from a overhanging ledge/cliff face.

Often triggered by freezing/thaw and from earthquakes.

talus

a sloping accumulation of angular, broken clasts piles at the base of a cliff that is subject to rockfall. Presence of this is good evidence that the cliff above is undergoing rockfall. Usually lie at or near the steepest slope angle.

avalanche

a fast mass movement process where much of the material is pulverized (broken into small powdery fragments) and then flows rapidly as an airborne density current. They can be made of snow, pyroclastic material, rock, and debris. They are powerful, can travel 60mph and can knock down tress and demolish buildings.

slides

A fast mass wasting event where a cohesive or semicohesive unit of earth material slips downslope in continuous contact with the land surface. Water plays a greater role in this compared to falls. If they contain large units of bedrock they are categorized as rock-------. They can also consist of debris, land and mud. They vary in size and anything in its path is obliterated.

slump

rotational slides where a thick block of soil (earth) moves along a concave, curved surface. because the curved surface of failure the slump undergoes a backward rotation as it slides causing the initial ground surface at the top of the slump to tilt backward. most common in wet years/wet seasons/areas of great relief.

landslide

large, rapid mass wasting events that are difficult to classify because they contain elements of more than one category of motion or because multiple types of material are involved in a single massive slide.

debris flow

originating on steep slopes rain/meltwater flush weathered rock from steep slopes into canyons. Chaotic saturated mixture of fine and coarse sediment ranging in size from tiny clay to large boulders. Can spill out the sides to create levees.

mudflow

steep slopes covered with huge amounts of volcanic ash become saturated when steam from the volcano comes down as rain. (add to this definition)

lahar

mudflows that are composed of volcanic ash. (fast moving volcanic mudflows)

flows

mass wasting event where masses of water-saturated unconsolidated sediments that move downslope by the force of gravity. These carry water in moving sediments.

subsurface water

general term for all water that lies beneath the surface. Water in soil, sediments, and rocks arrive from precipitation.

infiltration

water from precipitation or meltwater that soaks into the ground. In this process water moves from the ground surface into void spaces and loose sediments and into cracks joints and other fractures in rock.

recharge zone

where infiltration replenishes/adds to the amount of water in subsurface locations. The water then flows onto the surfaces into bigger bodies of water and supports substantially to those water levels.

zone of aeration

the area water initially passes through. pore spaces in the soil and rocks almost always contain some air and some water in turn makes the area very porous. This uppermost zone rarely becomes saturated.

percolation

when the zone of aeration become fully filled with water then water will soon drain downward beyone the zone of aeration by gravity.

soil water

Water in the zone of aeration.

zone of saturation

the lowest of the three layer of underground water where the openings are completely filled with water.

groundwater

Water in the zone of saturation is what this is called.

water table

a surface that marks the upper limit of the zone of saturation. It does not remain at a fixed depth but it fluctuates by different variables and generally takes the form of the landscape. it generally reflects the precipitation. (closer in humid regions and deeper underground in arid regions). If the water table is high in low elevations it could creates marshes or swamps.

intermediate zone

In the middle of the zone of saturation and aeration. This level is saturated during periods of wet but not saturated in periods of dry.

water mining

withdrawing water faster than it can replenish. It is called this to emphasize that groundwater resources are of limited supply and will not last indefinitely.

porosity

the amount of space between the particles that make up sediments or rocks. It is expressed as the volume of voids compared to the total volume of the material (including voids) depends on packing and uniformity of the grain sizes.

\-controls the potential amount of groundwater storage by providing available space for the water to be held.

permeability

how easily water flows through void spaces in earth material. Joints/fractures provide interconnections which help with flow.

\-affects the rates and volumes of groundwater movement and is facilitated by the presence of large pore spaces, bedding planes, joints, faults, and even caverns.

aquifer

a sequence of porous and permeable layers of sediments or rocks that act as a storage medium and transmitter of water. Usually made of sandstone, limestone, sand, or gravel.

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\[aqua - water ; ferre - to carry\]

aquiclude

a rock layer that is relatively impermeable (shale or slate) that restrict the passage of water

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\[aqua - water; claudere - to close off\]

perched water table

an accumulation of groundwater above an aquiclude. This also often prevents the downward percolating soil from reaching the zone of saturation. If water goes past this by drilling the water would be harder to get.

spring

natural outflow of groundwater to the surface. water comes from one primary spot and can form damp ground, pools, ponds, or irregular wetlands. if the water table remains at a level lower than a perched water table then a spring could flow continuously rather than intermittently (otherwise only flows when water table is high enough).

\-locations are determined by landform config., bedrock structure, elevation of water table, and relative positions of aquifers and aquicludes.

well

artificial openings dug or drilled down to a point below the water table to extract groundwater. wells that penetrate below the zone of water table fluxuation are more reliable.

artesian

groundwater rises to a level above the water table within the artificially excavated ___. The height depends on the natural pressure exerted on the water.

flowing artesian flows out under its own pressure without pumping. nonflowing artesian brings water above the local water table but not to the point of flowing out of the well.

acid mine drainage

when subsurface water becomes highly acidic as it moves through underground mines or mine tailings and it then undergoes chemical reactions leaving the water highly acidic and metal rich. The low mineral content and low pH endanger aquatic organisms and make the water not consumable to humans.

\-it is a serious environmental concern and it can be limited by controlling underground water flow.

karst

landform features created by the dissolving of calcium carbonate (limestone); constant water flow.

\-conditions: warm humid climate, ample precip., carbon dioxide, and subsurface water movement.

sinkhole

circular surface depressions that are prominent features in karst landscapes. This is because of the intense solution eroding at the cross cutting joints. They can result from excessive groundwater withdraw or from significant drought periods.

solution sinkhole

depression results from primary surface or near-surface solution of rock and removal of dissolved materials by water infiltrating downward into the subsurface. tend to be funnel shaped.

collapse sinkhole

when the land surface caves into large subsurface voids created by solution of bedrock some distance beneath the surface. Tend to have steep walls.

uvala

sinkholes that can grow in area and merge over time to form larger karst depressions.

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\[valley sink\]

disappearing stream

surface streams flowing on bedrock of low permeability upstream encounter a highly permeable rock downstream where they rapidly lose surface flow to infiltration. they “vanish” because they disappear into the subsurface.

cavern

a system of connected passageways where limestone used to be. If the water table falls and these passageways are above the zone of saturation then they are ___.

swallow hole

the site where a surface stream disappears into a cavern system. sometimes they reemerge at the surface as springs.

(where valleys are a stream used to be?)

haystack hill

only limestone remnants are left standing above insoluble rock below. They take the form of small steep sided and cave riddled karst hills. numerous ones take the shape of an egg carton.

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\[conical hills\]

tower karst

when limestone (haystack) hills are particularly high and steep sided

spleleothem

generic term for any chemical precipitate feature deposited in caves. they are in a great variety of textures and shapes. they originate when previously dissolved substances (calcium carbonate) precipitate out of subsurface water.

stalactite

when dripping water leaves behind a deposit of calcium carbonate that is termed dripstone. Hanging from a ceiling.

stalagmite

when calcium carbonates drips onto the floor of a cavern and is a more massive structure.

Artesian Spring

pressurized groundwater resources; the water is under so much pressure that if it finds an outlet it will flow upward to a level above the local water table. when it achieves a natural flow then it is an artesian spring.

\-conditions: a permeable aquifer must be exposed at the surface in an upland area that receives a high recharge by precipitation. must receive water by infiltration, incline downward hundreds of meters and be confined between impermeable layers that prevent the escape of water except to the artesian spring. (basically a pipe)

Regolith

The inorganic portion of soils.

unloading

erosion stripping of overlying rocks; removal of overlying weight. High elevation increases the process.

Granite exfoliation domes

an unloaded exfolitating outcrop of rock with a domelike surface.

exfoliation

removal of outer rock sheets

Hot Spring

a geothermal waterflow that flows onto the surface fairly continuously.

Geyser

a geothermal waterflow that is intermittent and produces steam and waterflow coming out of a vent.

subsidence

extensive pumping causing sinking of the land (compactation).

surface water

surface water shapes landforms and landscapes and creates others.

fluvial geomorphology

The study of flowing water as a land-shaping proess, together with the study of the resulting landforms. It includes the action of channelized and channelized flow moving downslope by the force of gravity.

interfluve

The land between adjacent channels in a stream dominated landscape.

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\[inter -between, fluvius - river\]

interception

precipitation being taken by vegetation for it allows greater infliltratration by slowing down the rate of delivery of precipitation to the ground.

sheet wash

at the begining of surface runoff, it starts to flow downslope as a thin sheet of unchannelized water. It starts to move into depressions in the terrain.

rill

concentration of flow leads to the formation of tiny channels that are typically centimeters.

gully

somewhat larger channels originating from rills. can be a couple of meters

ephemeral flow

channels that are empty of water much of the time. They only flow shortly after precipitation.

perennial flow

\-when downslope direction the smallest rills typically join to form slightly larger rills which can join to make cullies.

\-When it is a humid climate these can get longer and longer to the point where they flow all year. they may not flow throughout the year with the same volume or at the same velocity.

\-base flow: slow moving groundwater that seeps directly into the stream through the channel bottom and sides at and below the level of the water surface.

drainage basin

the expanse of land from which it recieves runoff. Drainage area refers to the measured extent of a drainage basin expressed in km2 or mi2. They are an open system of water sediment and energy. Also helps to track pollution.

drainage basin also constitutes part of the drainage basin of the trunk stream. small tributary basins are nested within called subbasins of succession and larger trunk streams drainage basins.

drainage divide

Outside perimeter of a drainage basin and the boundary between it and adjacent basins. it is generally higher land than the basin and is sometimes ridge shaped. the continental divide is an example in NA.

stream order

desribes quantitatively the position of a stream and its drainage basin in the nested hierarchy of tributaries

first order - source area (no perennial tributaries)

second order -two first order streams comb.

third order - intersection of two second order channels

etc. (mississippi 10th order)

exterior drainage

drainage basins with channel systems that convey water to the ocean. “stream mouth” (ultimate base level)

interior drainage

do not have enough flow to reach the ocean but terminate instead into local or regional areas of low elevation. (regional base level)

base level

elevation below which it cannot flow. sea level is the ultimate base level for virtually all stream action; this is where streams with exterior drainage reach. the low point of flow for a stream with interior drainage is regional base level. resistant rock layer upstream from the river mouth can act temporary base level until the stream can cut through.

drainage density

the total length of all channels in a drainage basin divided by its drainage area. high drainage densities have limited infiltration considerable runoff and at least moderately erodible surface materials. \[the more drainage density the less permeability???\]

drainage pattern

network odf stream tributaries display distinct spatial arrangements. The two main influencing factors are bedrock structure and surface topography.

patterns

dendritic=branching tree at acute angles; trellis= long parallel streams with short tributaries entering at right angles; radial=streams flow away from a common high point like cone(volcano); centripetal = streams converging on a central lowland; rectangular= blocky network of straight channels with right angle bends; deranged= streams flow on low gradient terrain left by receding glaciers (chaotic pattern)

stream discharge

describe quantitatively the amount of flow being conveyed through a stream channel. Expressed as Q and formula Q=Av. streams in a larger basin have greater discharge and are longer. an increase in stream velocity causes the channels to adjust and so the discharge increases.

stream load

sediment being transported by a stream.

stream competence

the maximum size of rock particles that a stream is able to transport

stream capacity

the total amount of load a stream is able to move. it depends on available stream energy and thus on the flow velocity. it increases when there is an increase in velocity

degradation

net erosion results in the lowering of the affected part of the landscape.

aggradation

net deposition of sediments results in a building up of the landscape. (vis a vis)

corrosion

when stream water chemically dissolves rock material and then transports the ions away in the flow.

hydraulic action

physical process of stream water alone removing pieces of rock. it depends on volume of water, flow velocity, flow depth, stream gradient, friction with the streambed, strength and size of rocks, and degree of stream turbulence.

abrasion

as rock particles bounce, scrape and drag along the bottom and sides of a stream channel they break off additional rock fragments.

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attrition is the wear and tear experienced by sediments as they tumble and boutnce against one another.