Thursday, September 19, 2013
Last week, we were back on the road again between Washington and Minnesota. It was a fairly quick trip, so there wasn't much time to explore, but I did find one beach worth noting. I found it early the third morning of the trip pretty much by accident, since I was only looking for early sun on the Big Horns northeast of Buffalo (Wyoming). I came around the corner and here was this wonderful red gravel beach!
Lake DeSmet began as a natural lake, although it has since been enlarged and turned into a reservoir.
Google Maps: Aerial View
The hills surrounding the lake are Tertiary sedimentary rocks, marked by resistant outcroppings of clinker. Clinker is a red or black rock that results when coal seams burn and bake the overlying sediments (see Callan Bentley's Mountain Beltway Blog at AGU). It's common in the Powder River Basin (because there's so much coal - see hshipman: Black Thunder Mine 2012).
This beach was at the south end of the lake, next to the dam, and consisted entirely of gravel-sized clinker. There were a series of berms marking higher lake levels. The beach was swash-aligned, oriented pretty much straight into the northwesterly fetch - the winds can get pretty fierce around here.
Farther west, the red gravel stacked up nicely against the limestone riprap of the dam. And at the boat launch on the southwest corner of the lake, there was a neat little clinker spit built across the mouth of a drowned creek mouth (drowned by the reservoir).
(For non-beach photos of our ten-day road trip:
hshipman: roadtrip 2013)