GEOL 100: Deserts

Where do Midlatitude deserts form? (3)

• between 30° to 50° latitude

• north or south of equator

• atmospheric air is sinking and warming

Where do semiarid deserts form? (3)

Interior regions of continents like China, Australia, and the Colorado Plateau (W. North America)

Where do Coastal deserts form?

Adjacent to cold ocean currents→ W. South America, South Africa, and S. CA coast

How and where do polar desert form? (A, G, A, C, S)

Cold atmospheric air sinking → Antartica, Greenland, Alaska, Canada, and Siberia

Where do rain shadow deserts form?

Leeward sides of mountain ranges where dry air is sinking

Sand dunes are the result of what?

Wind erosion and deposition

What are is the shape of barchan sand dunes? Where does it form?

1. Crescent-shaped; points downwind

2. Form from a single dominant wind direction in an area of limited sand supply

Transverse and barchanoid sand dunes are what shape? How do they form?

1. Straight and elongate

2. Perpendicular to a single dominant wind direction in an area with a large sand supply

Parabolic sand dunes are what shape? They form around what? (hint: same shape as Barchan but opposite point)

1. Crescent-shaped; pointed upwind

2. Blowouts from a single dominant wind direction in an area with large sand supply

Longitudinal (or Seif) sand dunes are what shape (4)? How do they form?

1. extremely long, straight, tall, and regularly spaced

2. Form parallel to the prevailing wind direction from a large supply of sand 

Star sand dunes indicate what?

A changing wind direction

What other deserts features can wind erosion result in? (P, V, Y)

Pavement, ventifacts, and yardangs

The colorado plateau consists mostly of what? What is it dominated by?

1. Flat-lying sedimentary rocks

2. Erosional landforms like plateaus, mesas, buttes, cuestas, hogbacks, and monoclines

The Basin and Range is a series of what? What is it dominated by?

1. Fault-bounded mountain ranges separated by flat valley floors

2. Despositional landforms like alluvial fans, bajadas, playas, and playa lakes

Dust Storms and Haboobs can occur where? Where are they the most common?

1. Anywhere in the U.S

2. Southwest