Ripples and plane beds

The Cutoff Formation, currently exposed in the Guadalupe Mountains in Texas, USA, was deposited over a drowned shelf margin in Permian times. The name of the formation is derived from subsequent erosion of its strata, which left the shelf, shelf margin and basinal domains in isolated sections. The field photo shown here is from the basinal part of the formation, in which coarsergrained intervals can be found in the form of deepwater channel systems deposited by low-density turbidites. The aggrading ripples and plane beds that can be seen in this beautifully exposed section are interpreted as part of the levee system associated with one of those deepwater channel systems.