Posted by: paulgarner | July 16, 2010

Buckskin Gulch and Kodachrome Basin State Park

This afternoon we made a four mile round hike into Buckskin Gulch, just off Highway 89 in southern Utah. It was extremely hot, 102 degrees when we left the car and probably even warmer inside the gulch itself. As John commented, “it’s like doing geology in your oven”! We hiked down through the Kaibab Formation, then the Toroweap Formation and eventually into the Coconino Sandstone and the underlying Hermit Formation. Having reached that point, we sampled the uppermost Hermit, right the way through the Coconino, and into the lowermost Toroweap. These samples will be used for thin section studies. We noted what appeared to be carbonate horizons within the Coconino, which we shall examine very carefully. The photograph shows the Hermit-Coconino contact in Buckskin Gulch; the Hermit is the reddish formation below the paler Coconino Sandstone.

Earlier in the day, en route from Escalante to Buckskin Gulch, we took a short detour into Kodachrome Basin State Park to see the famous clastic pipes. These are vertical sandstone pillars that formed when wet, unlithified sediments were intruded into the overlying strata. Sixty seven of these pipes have been mapped in this area. In many cases, the sediments into which the pipes were intruded have been wholly or partially eroded away, leaving these extraordinary pillar-like structures towering over visitors to the park. However, as Ariel Roth explains in this article, these structures have some implications for geological time scales. From a conventional perspective, the time of intrusion may have been as much as 150 million years after the sediments were originally laid down, so how did they remain wet and unlithified for so long and under such a large overburden of other strata? The intrusion of these pipes seems consistent with a much shorter time scale for the deposition of these sedimentary layers than most geologists are willing to contemplate. The photograph shows one of the thinner pipes we saw today.



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