21 August 2011
The best cross-bedding you’ll ever see
Posted by Callan
Setting aside the lack of scale, it really doesn’t get any better than that. Click through to make it huge.
This is the Navajo Sandstone, early Jurassic (or late Triassic?) in age. It’s in Zion National Park, Utah. Wind direction was from the right towards the left, as these preserved slip-faces of ancient dunes indicate. The beds are right-side-up, and they have been differentially eroded, causing the cross-beds to jump out in high-relief when lit by the sun directly overhead.
Nine main beds; infinite cross-beds, and also note the joint set orthogonal to the cross-beds.
Callan Bentley is an assistant professor of geology at Northern Virginia Community College in Annandale, Virginia. He is particularly interested in structural geology and the evolution of the Appalachian mountain belt. Callan draws cartoons and writes for EARTH magazine. He lives in the Fort Valley of Virginia.
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