Exam 13: Deserts and Wind Action

Where sand supply is limited a barchan dune generally develops.

_______ is a thin surface layer of closely packed pebbles found in deserts.

A _____ is a depression on the land surface caused by wind erosion which may have a pillar left at the center.

Most sand dunes are asymmetric in cross section with a gentle slope facing the wind and a steeper slope on the downwind side.

A desert is any region which has a dry or arid climate with a low rainfall of less than 25 cm per year.

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

This agent of erosion and deposition is most effective on fine sediment that is dry.

Loess deposits in the U.S. Midwest are derived from ____.

A large dune type is the _______ (or seif) dune, which forms a ridge parallel to prevailing wind direction.

Ventifacts are rocks with rounded water-abraded surfaces.

Dune types are influenced by wind velocity.

Rapid down cutting of desert stream channels produces narrow canyons with vertical walls and flat gravel-strewn floors.

This area of the desert southwest is characterized by mostly flat-lying beds of sedimentary rock over 1,500 meters above sea level.

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

Deflation continues to deepen a blowout until it reaches ______.

Dune sand throughout the world is composed of the stable mineral quartz.

Sand grains found in dunes are commonly _______.

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

How do deserts form in coastal tropical regions?

Loess is a deposit of wind-blown silt primarily composed of unweathered angular grains of quartz and feldspar.