Exam 18: Deserts and Wind Action

High-speed winds can cause ____,clouds of sand moving rapidly near the land surface.

Where sand supply is limited a _____ dune usually forms.

In the United States,large areas of _____ are blanketed with a cover of loess.

The removal of clay,silt,and sand particles from a land surface by wind is called _____.

A(n)_____ is a broad gently sloping surface formed by the coalescing of alluvial fans.

_____ is the dominant agent of erosion in desert regions.

A ____ dune is deeply convex and its horns point upwind.

Wind-blown sand may sculpt isolated pebbles,cobbles,or boulders into ____.

Since many desert regions have internal drainage,runoff collects on the valley floors as bajadas.

Sand moving over a dune surface by saltation typically forms ___.

_______ has extensive loess deposits up to 100 meters thick.

When the desert sun dries a lake,a very flat surface underlain by hard mud-cracked clay called a _______ may form.

Because sand grains are heavier than clay and silt particles,sand grains move close to the ground in a leaping pattern called ______.

_______ dunes in the Sahara are as high as 200 m and as long as 120 km.

Because sand-sized grains are heavier than silt or clay-sized grains,sand moves close to the ground in a series of short hops called saltation.

A(n)____ is a gently sloping erosional surface,commonly covered with a veneer of gravel,cut into the solid rock of a mountain.

A playa lake is a deep long-lasting desert lake.

Ventifacts are rocks with rounded water-abraded surfaces.

The angle of repose of sand-sized particles falling from the air is _____ degrees.

U.S.deserts in Nevada and northern Arizona are largely the result of the Sierra Nevada Mountains ____.