Many veterans of the Wooster Geology expeditions to southwestern Utah will remember the insatiable, abundant, nearly overwhelming biting gnats that occasionally proliferated during our fieldwork. We’ve suffered them each day, but this was the worst experience thus far, mainly because we were collecting data in a nearly windless wadi at their mercy. (Image by Nick.)
But first, our day began with another section for Lucie’s Independent Study project, this one on the Eagle Mountain Ranch at N 37.307688°, W 113.739697°. Above is a ghostly, pensive Lucie in the shadows waiting to scramble up from the base of her section. It is again a stromatolitic sequence, this time with desiccation cracks and a top layer of calcitized gypsum nodules. Above this we eventually reached the lower oolitic shoal deposits of the upper unit. It all went as planned, with critical stratigraphic measurements (and structural observations) from Nick and Shlley.
After lunch was our descent into Buggy Gulch, otherwise known as the Manganese Wash section we measured, sampled and described on Sunday (N 37.283125°; W 113.803696). Beautiful day for us and, unfortunately, the clouds of gnats. We were stuck in place measuring current ripples and cross-bedding in the main oolitic shoal deposits. Shelley showed us how to do the work with her mad structural geology skills. We collected a boatload of data at the expense of our sanity. I’m scratching bites as I write this.
Bug complaints aside, the sedimentary structures here are well developed. Here is a set of current ripples with easily-measured crests and clear directional indicators.
The cross-sections through the shoals display complex cross-bedding, the product of multiple changes in current directions and velocities. This is important data for our paleoenvironmental reconstructions.
Finally, we’ll end the day with a gorgeous prickly pear cactus flower, suitably crawling with insects.
