Date of Award


Document Type


Degree Name

Master of Science (MS)



First Advisor

F.D. Holland, Jr


Fossil gastropods were studied from the upper part of the Pierre shale (Upper Cretaceous) in Emmons County, south-central North Dakota. This primary purpose of this study was to figure all gastropods found and bring the nomenclature of up to date. Secondly, an attempt was made to determine whether these fossil gastropods could be used in defining the contact between the Pierre shale and overlying Fox Hills sandstone.

Little paleontological work has been done on Pierre gastropods in North Dakota. Identification previously made seem to have been done somewhat hurriedly from Meek (1876) with little regard to modernizing the nomenclature.

These gastropods were collected from fine-grained gray limestone concretions at the top of the Pierre shale from two localities southeast of Linton in central Emmons County. The gastropods were usually found well preserved but were commonly partly or whelly broken when trying to free them from the hard dense limestone concretions.

The Pierre shale exposed Emmons County belongs to the uppermost member of the Pierre, the Elk Butte, which is typically developed in northcentral South Dakota. The contact with the overlying Fox Hills sand stone is apparently gradational. This evidenced by the occurrence of many common species of gastropods in both formations near the contact, which brought out by this and previous studies in the Western Interior.

Fourteen species of gastropods were arranged in 12 genera. Of the 11 forms identified to species, 10 of these have previously been reported to occur in both Pierre and Fox Hills formations. From the evidence at hand, it does not seem likely that gastropods can be used in defining an accurate Pierre-Fox Hills contact. However, this common occurrence of gastropods does serve to strengthen the accepted concept of gradational contact between the Pierre and Fox Hills formations.

Cvancara (76896 kB)

Included in

Geology Commons