The gneiss that is found in Joshua Tree National Park is nearly the same as that found in Australia and in Antarctica. These two continents, along with North America, were once connected to each other, forming a super-continent that is known as Rodinia. The Joshua Tree gneiss was likely part of the Rodinian Mountain chain that spanned across Rodinia, until Rodinia broke up, roughly 800 million years ago.
After the break-up of Rodinia, the Joshua Tree rocks lay submerged for another 250 million years.
Both of these photographs were taken at "Jumbo Rocks."
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