Hundreds of concretions litter the stream bed of Deer Creek in Pickaway County, Ohio. These concretions are composed of siderite, a type of iron carbonate, and many are massive. Over the eons, they have eroded from the much softer Devonian Shale. Shale cliffs line the western bank of the stream. The overall effect is quite dramatic and more than a touch surreal. It's like an army of rock blobs marching down the stream. I hope to get back here near the peak of fall color for more photography. Yesterday morning.