Cretaceous sandstone layers, exposed on the Blackfeet Reservation (Montana route 49), east of Glacier National Park, Montana. Apparently these two are the opposite halves of the same jointed block.
Cretaceous sandstone layers, exposed on the Blackfeet Reservation (Montana route 49), east of Glacier National Park, Montana. Apparently these two are the opposite halves of the same jointed block.
Is this the same thing as plumose structures just in a circular form?
They are both different aspects of joint anatomy, with the concentric ribs being perpendicular to the plumes.