Exhumed river channel

An exhumed river channel is a ridge of sandstone that remains when the softer flood plain mudstone is eroded away.

Minerals (typically calcium carbonate) can cement the grains together converting the loose sand into sandstone.

Millions of years later, erosion can remove the softer, less cemented mudstone and leave the more resistant sandstone as a sinuous ridge.

Thus, an exhumed river channel is a form of inverted relief: what was previously low is now high, and vice versa.

Within the Cedar Mountain Formation in this part of Utah, fluvial sandstones filling paleochannels within it are cemented by calcium carbonate.