Geography Exam 5

Erg

"sea of sand" A large area covered with loose sand, generally arranged in some sort of dune formation by the wind

Cut Bank

(Outside of curves) where water moves fastest and cuts the bank

How much of the land was ice-covered at the max extent of Pleistocene Glaciation

1/3

How many glacial periods were there in Pleistocene Glaciation

18 or 19

When was Pleistocene Glaciation

2.5 million ybp to 10,000 ybp

How many desert streams are ephemeral

99%

Hamada

A barren desert surface of consolidated material that usually consists of exposed bedrock but it is sometimes composed of sedimentary material that has been cemented together by salts evaporated from groundwater

Barchan Dune

A crescent-shaped sand dune with cusps of the crescent pointing downwind

Desert Varnish

A dark, shiny coating of iron and manganese oxides that forms on rock surfaces exposed to desert air for a long time

Reg

A desert surface of coarse material from which all sand and dust have been removed by wind and water erosion. Often referred to as desert pavement or desert armor.

Valley Glaciers

A long, narrow feature resembling a river of ice, which spills out of its originating basins and flows down-valley

Sand Dune

A mound, ridge, or low hill of loose, windblown sand.

Perennial

A permanent stream that contains water year-round

stream capture

A portion of the flow of one stream is diverted into that of another by natural processes.

Knickpoint

A sharp irregularity in a stream-channel profile (waterfall)

Cirque Glacier

A small glacier confined to its cirque and not moving down-valley

Ephemeral

A stream that carries water only during the "wet season" or during and immediately after rains.

Ephemeral Stream

A stream that carries water only during the "wet season" or during and immediately after rains.

Intermittent

A stream that carries water only part of the time, during the "wet season" or during and immediately after rains.

Exotic Stream

A stream that flows into a dry region, bringing its water from somewhere else

Point Bar

Accumulation of alluvium

Downcutting

Action of stream to erode a deeper channel; occurs when stream is flowing swiftly and/or flowing down a sleep slope

Rock Fragments

All rocks chip and grind the scrambled, break off fragments from the bottom and side and become smaller

Pleistocene Glaciation

Alternation of glacial and interglacial periods

Drainage Basin (Watershed)

An area that contributes overland flow and groundwater to a specific stream.

Base Level

An imaginary surface extending underneath the continents from sea level at the coasts and indicating the lowest level to which land can be eroded.

Alluvium

Any stream-deposited sedimentary material

4 Types of Active Dunes

Barchan, Transverse, Seifs, Star Dunes

Undercutting

Causes landslides that dump more loose material into the water to be swept downstream.

Streamflow

Channeled movement of water along valley bottom.

2 types of non-arid dunes

Coastal Dunes, Loess

Stream Order

Concept that describes the hierarchy of a drainage network. (orders)

continental glaciers

Continental ice sheets, outlet glaciers, ice shelf, ice berg

How does turbulence influence erosion capability?

Creating flow patterns that pry and lift rock materials from the streambed.

Transverse Dune

Crescent-shaped sand dune ridges that have convex sides facing the prevailing direction of wind and which occur where the supply of sand is great. The crest is perpendicular to the wind direction vector and aligned in parallel waves across the land

Three different features found in the floodplain

Cutoff meander, natural levee, yahoo stream

Three theories of landform development

Davis's Geomorphic Cycle, Penck's Theory of Crustal Change and Slope Development, Equilibrium Theory

5 Drainage Patterns

Dendritic, Trellis, Radial, Centripetal, Annular

Subsequent Stream

Develop along zones of structural weakness

Trellis

Developed on alternating bands of hard and soft strata, with long parallel subsequent streams linked by short, right-angled segments and joined by short tributaries

Playa

Dry lake bed in a basin of interior drainage

Salina

Dry lake bed that contains an unusually heavy concentration of salt in the lake-bed sediment

Desert Landscapes

Erg, Reg, Hamada

Consequent Stream

First to develop on newly uplifted land and many streams remain consequent throughout development

Floodplain

Flattish valley floor covered with stream-deposited sediments (alluvium) and subject to periodic or episodic inundation by overflow from the stream.

Radial

Found when streams descend from some sort of concentric uplift, such as an isolated volcano.

Continental Ice Sheets

Glaciers that form in non mountainous areas of the continent

Flow Speed

Governed by the gradient of the scrambled, the shape of the channel, and the volume of the flow.

Salina Lake

Great Salt Lake, Utah

Desert Pavement

Hard and relatively impermeable desert surface of tightly packed small rocks

mountain glaciers

Highland Icefields, valley glaciers, alpine glacier, cirque glacier, piedmont glacier

Ice Berg

Huge floating ice mass

Superimposed

Ignores local structure, original pattern erodes

Alpine Glacier

Individual glacier that develops near a mountain crest line and normally moves down-valley for some distance

Meandering

Intricate pattern of smooth curves, loops and curves

Highland icefield (nunatak)

Largely, unconfined ice sheet in high mountain areas

Outlet Glaciers

Long tongues of ice that extend between rimming hills to the sea

Seifs

Long, narrow desert dunes that usually occur in multiplicity and in parallel arrangement

Dissolved Load

Minerals and salts are dissolved in the water and carried in solution

Braided

Multiplicity of interwoven and interconnected channels separated by low bars or islands of sand, gravel, and other debris.

Example of an exotic stream

Nile River of North Africa

Splash Erosion

Particles that move downhill on sloping ground.

Indirect effects of Pleistocene Glaciation

Periglacial zone, sea-level change, crustal depression, pluvial developments, pluvial effects and pleistocene lakes.

Delta

Produced by the sudden reduction of a stream's velocity and the resulting deposition of the stream's load.

Ice Shelf

Projection of ice out over the sea

Star Dunes

Pyramid-shaped sand dune with arms radiating out in three or more directions

Abrasion

Requires "tools" in the form of airborne sand and dust particles. The wind drives these particles against rock and soil surfaces in a form of natural sandblasting

Gully Erosion

Rills coalesce into fewer and larger channels called gullies. The gullies get larger and larger until they incorporate into the drainage system of the adjacent valley.

Annular

Ring-shaped drainage either on a dome or in a basin

Saline Lake

Salt lake; commonly caused by interior stream drainage in an arid environment

Coastal Dunes

Sand dunes formed from sand being blown inland

Bedload

Sand, gravel, and larger rock fragments moving in a stream by saltation and traction.

Rill Erosion

Sheet flow is broken up into tiny channels called rills, the flow picks up additional material and scores the slope with numerous parallel seams

Straight

Short and uncommon

Corrosion

Soluble rock being dissolved by water.

four channel patterns

Straight, sinuous, meandering, and braided

Antecedent Stream

Stream that predates the existence of the hill or mountain through which it flows

Centripetal

Streams converging in a basin

Where did the ice in the Pleistocene Glaciation originate?

Subpolar and midlatitude regions

Valley

That portion of the total terrain in which a stream drainage system is clearly established.

How does flow speed relate to erosion

The erosive effectiveness of streamflow is determined by flow speed

Overland Flow

The general movement of unchanneled surface water down the slope of the land surface.

Graded Stream

The gradient just allows the stream to transport its load

Interfluve

The higher land or ridge above the valley sides that separate adjacent valleys; drained by overland flow.

Piedmont Glacier

The leading edge of a valley glacier reaches a flat area and escapes from the confines of its valley walls

Capacity

The maximum load that a stream can transport under given conditions.

Recurrence Interval

The probability of a given-size flood occurring in a year; also called the return period

Deflation

The shifting of loose particles by wind blowing them into the air or rolling them along the ground

Competence

The size of the largest particle that can be transported by a stream.

Suspended Load

The very fine particles of clay and salt that are in suspension and move along with the flow of water without ever touching the stream bed.

Dendritic Pattern

Treelike, branching pattern that consists of a random merging of streams with tributaries joining larger streams

Knickpoint Migration

Upstream shift in location of a knickpoint and due to erosion

Fossil Dune

Vast deposits of sandstone exhibit the characteristic of "cross-bedding" of wind-deposited sand, rather than the more typical horizontal strata of sediments accumulated in bodies of water

Stream Discharge

Volume or flow of a stream

Sheet Erosion

Water flows across the surface as a thin sheet, transporting material already loosened by splash erosion.

What conditions in deserts make them so different

Weathering, soil and regolith, soil creep, impermeable surfaces, sand, rainfall, fluvial deposition, wind, basins of interior drainage, and vegetation

Sinuous

Winding and found in every type of topographic setting

What glacial period ended Pleistocene Glaciation

Wisconsin (Wurm) Glaciation

Largest delta in the US

Yukon

Loess

wind-deposited silt that is fine grained, calcerous, and buff colored. found in midlatitudes: US, Russia, China, and Argentina