Specifically referred to as potholes, this feature was found in the long stretch of shut-ins of the St. Francis River between Silvermines Recreation Area and Millstream Gardens. Steve and I took this, one of our favorite hikes, this autumn, just before peak color came into this section of the Ozarks. Here is a wonderful description of this feature’s formation from Tom Beveridge’s Geologic Wonders and Curiosities of Missouri:
“Potholes are formed at the nearly right-angled intersection of channelways where the direction of flow is abruptly changed. The abrupt changes in direction of flow and the intersecting channelways create local whirlpools where the swirling waters grind out circular holes using sand and gravel carried in suspension as a natural abrasive. Man did not invent sandblasting – he only mechanized it! Deepening of the holes is also expedited by the steep gradient of the stream; some holes are in part plunge pools formed by the impact of water descending vertically and gouging out the bed at the base of individual waterfalls.”
See my Flickr account for similar images made on this day.
“All Seeing Eye”
A Thousand Acres of Silphiums 