Exam 13: Deserts and Wind Action

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

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

A mesa is capped by sedimentary rocks while a butte is capped by a lava flow.

Not all deserts are hot. Descending air near the North and South poles creates ____ deserts.

A ______ is a narrow hill of resistant rock with a flat top and very steep sides found in some deserts.

An area with desert conditions in the United States is ____.

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

Desert stream channels called ____ are characterized by narrow canyons with vertical walls and flat, gravel-strewn floors.

In passing over a dune, wind scours sand from the downwind or slip face.

The steep downwind face of a sand dune is called the ______.

Some of the world's deserts are the result of the rain shadow effect of mountain ranges.

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

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

Thin rocky soil and slow rates of creep make desert topography steep and angular.

The high runoff following sporadic desert downpours can create sudden local floods called ______.

A pediment is an erosional surface underlain by solid rock, while a bajada is depositional and is underlain by sediment.

_______ 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 broad gently sloping surface formed by the coalescing of alluvial fans.

The world's best-known deserts lie in a belt 10-15 degrees centered at latitude of 30 degree (North and South).