geog 2300E exam 3

define endogenic processes

build initial landscapes

define denudation

process that wears away or rearranges land forms

define dynamic equilibrium

the balancing act between rock being built up and broken down at the same time

define angle of repose

35 degrees for dry sand to become unstable

when is slope stable

if its strength exceeds the weathering/erosion processes

when is slope unstable

if its materials are weaker than the weathering/erosion processes

define weathering

the process of the landscape wearing down due to exposure to the elements 

define physical weathering

process of rock breakage without chemical alteration

define frost wedging

freeze/thaw action

define thermal expansion

materials expand/contract when subjected to changes in temperature

examples of physical weathering

frost wedging and thermal expansion 

define chemical weathering

decomposition/decay of the minerals in rock due to chemical reaction

examples of chemical weathering

spheroidal weathering, oxidation, and hydration/hydrolysis 

define spheroidal weathering

creates rounded landscape

define oxidation

when oxygen combines with substances in rock leading to rust

define hydration/hydrolysis

break down of materials in rock due to contact with water

define regolith

broken up rock due to weathering

define bedrock

parent rock from which weathered regolith/soil develops

define geomorphic threshold

gravity pulls on mass until the critical failure point is reached

define falls

rocks fall through air and hit surface bellow

define slides

sudden movement of cohesive mass that is not saturated with moisture

define flows

when moisture content in moving material is high

define creep

persistent mass movement of surface soil

define river

main stream of network of tributaries that form river systems

what always flows downhill

rivers

define stream

smaller/lower flow rates than rivers

what flows into rivers to form tributaries

streams

define erosion

water dislodges, dissolves, or removes weathered surface material

define deposition

material transported to new locations and deposited

define drainage basin

area where all flowing surface water converges to a single point or flows into another body of water

define rills

small grooves in earth’s surface made by downslope movement of water

define sheet flow

thin film of water that spreads over the surface

define continental divide

separates drainage basins that empty into different bodies of water surrounding a continent 

define drainage pattern

arrangement of stream patterns in an area

what can reveal characteristics of the kind of rocks/structures in a region

drainage patterns

define dendritic drainage

most common pattern that looks like tree roots

what develops in regions of homogenous material

dendritic drainage

define parallel drainage

forms on long uniform slopes that are steep

define radial drainage

occurs when streams flow off a central peak/dome like a volcano 

what develops around a central elevation point

radial drainage

define rectangular drainage

occurs when rocks are uniformly resistant to erosion

what develops in areas with little topography

rectangular drainage

define trellis drainage

occurs on landscapes with sedimentary rock and places where rocks have different strengths

define discharge

volume passing a point in a given unit of time

define fluvial processes

ongoing interaction between erosion, transportation, and depositions in a river system

define eolian

wind

define eolian processes

erosion, deposition, and transportation by wind

why are small particles difficult to move

they have mutual cohesiveness

why are intermediate particles easy to move

they can bounce along

define large particles

are heavy and require strong winds

define abrasion

grinding rock surface by the sand blasting action of particles captured in the air

define deflation

removing/lifting individual loose particles

define ventifact

rock exposed to eolian abrasion that are aerodynamically shaped based on wind direction 

define yardongs

large scale streamlining rock structures that are aligned parallel to the most effective wind direction

define desert pavement

surface layer of closely packed/cemented rock fragments from which fine material has been removed

how much of desert areas are covered with sand

10%

define crescent dunes

produced by wind flowing in one direction

define linear dunes

long, narrow dunes formed from shifting winds from 2 directions

define star dunes

formed when direction of wind changes often from different directions

define loess

materials blown great distances by the wind and redeposited in deep unstratified deposits 

define loess deposits

fertile soils due to deep soil depth and well drained characteristics 

what creates the breadbasket farming regions

loess deposits

define desertification

process by which fertile land becomes desert

define dust bowl

severe drought/failure to apply dry land farming methods to prevent aeolian processes