hot deserts key terms

Insolation

The incoming solar radiation that reaches the Earth's surface

Runoff

Water running over the surface

Sediment source

How the sediment enters the system

Sediment cell

The inputs, components (stores and transfers) and outputs in a system.

Sediment budget

The balance of inputs and outputs within a system

Geomorphological process

The physical and chemical changes which affect a modification of the Earth

Thermal fracture

The weathering of rock resulting from their rapid and repeated heating and cooling

Exfoliation

A process of mechanical weathering that results in the breaking, splitting or peeling-off of the outer rock layers (also known as onion skin)

Chemical weathering

The process leading to the decomposition or breaking down of rocks due to chemical reactions. This most often requires the presence of water, and/or exposure to the air

Block and granular disintegration

The splitting of rocks along the joints

Deflation

Where wind removes dry, unconsolidated (loose) sand, silt and clay particles from the surface and transports them away

Abrasion

Where material carried by moving wind or water hits exposed rock surfaces, wearing them away (sandblasting)

Suspension

The transportation by wind where the smallest particles (less than 0.2mm) are held in the air

Saltation

A process where sand-sized particles are bounced along the surface

Surface creep

Where saltating particles return and hit larger particles causing them to slowly roll or creep along the surface (they are too heavy to lift)

Deposition

Occurs when the velocity of the wind decreases until it can no longer transport grains it is carrying

Deflation hollow

When wind removes significant amounts of material from the surface

Aeolian landform

A natural geomorphic feature shaped by the wind

Desert pavement

A concentration of coarse pebbles after wind has removed the finer pebbles from the surface

Ventifact

Exposed rock lying on the desert surface that have been abraded by the wind

Yardang

A stream-lined parallel ridge of rock

Zeugen

The collective name for features such as rock pillars, rock pedestals and rock mushrooms

Barchan

Crescent-shaped sand dunes

Sief dunes

Knife-edged ridges of sand separated by wind-scoured depressions

Exogenous water

Water which originates externally to the desert

Endoreic water

Water occupying drainage basins which are closed and do not reach the sea

Ephemeral water

Water that flows intermittently

Sheet flooding

An expanse of moving water

Flash flooding

Rapid flooding of low-lying areas

Wadis

Steep-sided, wide-bottomed, gorge-like valleys

Bajadas

When alluvial fans coalesce

Pediments

Gently sloping areas of bare rock and debris

Playas

A dry lake bed

Inselbergs

Rounded steep-sided hills that rise abruptly from a lowland plain