Mojave River Valley Museum
Geology Tour Road:|
Old Erosional Level
Many of the monzogranite boulders here bear a distinct groove about seven feet above the
ground level. The sides of the boulders are generally steeper above this line than below it.
This line indicates where a stable soil existed, protecting the bottom of the boulder from
erosional forces during a wetter climate. Afterwards, during a drier climate, the soil surface
eroded more rapidly. During this period there has not been nearly as much time for the lower
surfaces of the boulder to weather, so the surfaces below the old soil level are not so steep.
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