erosion

Erosion in Montana is ,well,different.

Yacoraite Formation
Type Geological formation
Sub-units Amblayo, Güemes, Alemanía and Juramento Members
Underlies Olmedo Formation, Tunal Formation
Overlies Lecho Formation


The Yacoraite Formation is a largely Mesozoic geologic formation. The deposits of this formation mainly date from the Maastrichtian of the Upper Cretaceous, but the Cretaceous–Paleogene boundary (K–T boundary) runs right through this formation near its top, and the uppermost parts are consequently from the Danian (Lower Paleocene). It was probably deposited around the intertidal zone, as the sedimentary rocks of this formation alternate according to sea level changes between deposits of muddy beaches and of shallow ocean.[1]

In fact, the turtlebacks are complex three-dimensional entities that formed over ~ 14 m.y.
of extensional overprinting on an older Mesozoic framework. We submit that many of the controversies regarding the Death Valley region in general, and the turtleback systems in particular, stem largely from the inability to communicate observations of these multiple dimensions. Even the coauthors of this paper are not in complete agreement on several details, but our approach here is to clarify our view of the four-dimensional history.