Just east of the Mt. Carmel Tunnel lies Checkerboard Mesa, a remarkable example of crossbedding in Navajo sandstone, a mesa which you can’t help but notice along the highway. Over eons in what used to be a great desert, shifting sands deposited one layer after another, their orientations determined by winds, all eventually cemented over time. The vertical cracks along the mesa were formed by a process called jointing wherein stresses on the rock causes it to split. Weather and cycles of freezing and thawing also contribute to their pronounced expression.
Here, too, you can see the bleaching phenomenon that characterizes thick deposition of Navajo sandstone. Over vast spans of time (we’re talking millions of years), the iron oxide which gives the reddish appearance to the rocks drifts downward, or percolates, leaving the upper portions whitish in color.
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