A theory of the formation of this substance was supported by Wells and Olinger's measurements of helium-3 levels in the Cima dome, and posited that it formed at the same time as a nearby lava flow. Another theory of its formation includes the expansion and contraction of clays due to precipitation, leading to the surfacing 
A theory of the formation of this substance was supported by Wells and Olinger's measurements of helium-3 levels in the Cima dome, and posited that it formed at the same time as a nearby lava flow. Another theory of its formation includes the expansion and contraction of clays due to precipitation, leading to the surfacing of this substance's components. The most popular theory of its formation says that it's what's left behind after (*) deflationary processes remove smaller particles. This substance is supported underneath by an A-type vesicular soil horizon and is covered by an orange or black clay coating forming a similarly-named varnish. For 10 points, name this layer of interlocking pebbles and cobblestones found underneath sand in a certain arid biome.
A theory of the formation of this substance was supported by Wells and Olinger's measurements of helium-3 levels in the Cima dome, and posited that it formed at the same time as a nearby lava flow.
desert pavement