The Kreyenhagen shale at the type locality overlies with seeming conformity the Domengine (upper middle Eocene) sandstone and is overlain unconformably by beds of Temblor (lower middle Miocene) age. The Kreyenhagen is composed of shale of the kind generally characterized as an "organic shale," with a few lenses of fine-grained sandstone and limestone. Only one mollusk, Pecten interradiatus, was found in the shale. Foraminifera are ordinarily scarce and poorly preserved; and only a scanty fauna was obtained from the base of the formation. Radiolaria are plentiful throughout; diatoms, however, were not noticed.

The evidence at hand points to a deep marine basin as the place of deposition which was possibly within the bathybic zone, but in any event exceeded a depth of 50 fathoms. The temperature at the bottom was cool, although the climate on the land may have been tropical. The complexion of the foraminiferal fauna is more Eocenic than Miocenic. The stratigraphic position of the Kreyenhagen between Domengine (middle Eocene) and Temblor (middle Miocene) proves that it is upper Eocene, Oligocene, or lower Miocene in age. Paleontologic evidence as well as the unconformity between the Kreyenhagen and the Temblor suggests an Eocene or Oligocene rather than a Miocene age for the Kreyenhagen shale.