Isolated Bones Unit. This thick layer above the Isolated Bone Unit is made up of very homogenous claystone/siltstone that is relatively barren of dinosaur bones or plant material. It is considered overburden in the digsite areas.
Mixed Lithology Unit. The stratigraphy of this next layer is complex, with multiple alternating cycles of sedimentation occurring in both humid and semi-arid environments. Sandstone channels are visible, as well as thick, very fine-bedded siltstones, some hardpans and even layers full of small rounded pebbles and rounded dinosaur bone pieces. These Mixed Lithology layers range from thin to over two feet in thickness, with repetitive cycles emerging vertically.
Scattered Bone Unit. This topmost layer could likely be a reworked section of the lower Mixed Lithology Unit, where previously deposited sediment was transported and re-deposited during flooding events. Details of this layer are not yet well-defined, as it is mostly considered overburden that has to be removed to be able to reach the underlying dinosaur bone-bearing sections.
