Return to Marble Canyon

The famous crossroads sign at Marble Canyon

My most recent trip was mostly return visits, and since I've written on the exploration of Marble Canyon before, I figured I could now write the Informing part of it. This part of the Cottonwoods, including Marble and Cottonwood Canyons, is almost entirely end-paleozoic era limestones and marbles between 350 and 290 million years old. A lot of the rock along the canyon includes black balls and lumps of a microcrystalline chert. These result from colonies of algae that have fossilized and stand out prominently against the grey limestone.




The lower canyon where most travel is entirely made up of the Pennsylvanian-era Bird Springs Formation, which was deposited on a continental shelf off the coast of North America some 310 Million years ago. Rocks in this area have been studied extensively as part of a study on sea level changes off the coast of North America in prehistoric times. For further reading check out the most recent paper on the area, published in 2014 by the USGS. PDF of map here.

The sign from the road

Marble Canyon Road

Fossil clam shell in limestone

Canyon cutting through the mountain

Fossilized algae clumps have turned into cherty inclusions.
Stone Canyon Limestone.

Excellent bedding here, part of the Bird Springs Formation.

Chert nodule

Excellent nodule

Here what is probably the Osborn Canyon Formation is cut by the wash, creating a
dramatic "Bathtub" amphitheater.

The narrows cut through a wide swath of Santa Rosa
Hills Limestone that has been faulted into place.

Huge breccia cemented by quartz. Large chunk at top approximately
20 inches long.

The bulk of the canyon is this stuff; the Pennsylvanian Bird Spring
Formation.