Now for a .EDU moment while I figure out what some of these terms are:

The surface of the dry lake is referred to a Alluvial.

From Wikipedia, the free encyclopedia

"Alluvial" redirects here. For the American racehorse, see Alluvial (horse). For the type of flow diagram, see Alluvial diagram.

Section of alluvium at the Blue Ribbon Mine in Alaska

Alluvium deposits in the Gamtoos Valley in South Africa

An Alluvial plain in Red Rock Canyon State Park (California)

Alluvial river deposits on the Amazon Basin, near Autazes, AM – Brazil. The seasonal deposits are extremely fertile, and crucial to subsistence farming in the Amazon Basin along the river banks.

Alluvium (from the Latin, alluvius, from alluere, "to wash against") is loose, unconsolidated (not cemented together into a solid rock)soil or sediments, which has been eroded, reshaped by water in some form, and redeposited in a non-marine setting.^[1][2] Alluvium is typically made up of a variety of materials, including fine particles of silt and clay and larger particles of sand and gravel. When this loose alluvial material is deposited or cemented into a lithological unit, or lithified, it would be called an alluvial deposit.

In the case here of El Mirage the surface of the dry lake is a clay that creates the driving surface, amazingly flat without bumps or surface disturbances that make it ideal for high speed vehicle test drives.

Playa

From Wikipedia, the free encyclopedia

Look up playa or playas in Wiktionary, the free dictionary.

Playa (plural playas) may refer to:

Contents

  [hide] 

• 1 Landforms
• 2 Named playas
• 3 Populated places
• 4 Other
• 5 See also

Landforms[edit]

• Sink (geography), also known as an alkali flat or sabkha, a desert basin with no outlet which periodically fills with water to form a temporary lake
• Dry lake, commonly called a playa in the southwest US and Mexico
• Playa is the Spanish language word for beach