Date of Award


Document Type


Degree Name

Master of Science (MS)



First Advisor

F.D. Holland, Jr


The thesis here abstracted was written under the direction of F. D. Holland, Jr., and approved by Wilson M. Laird and Walter L. Moore as members of the examining committee, of which Dr. Holland was chairman.

The “Heath” Formation, between the underlying Otter and the overlying Amsden(?) Formations in the subsurface of southwestern North Dakota, is a source of petroleum in the Scoria-Fryburg, Rocky Ridge and Dickinson oil fields. Cores, cut from the interval under study, of twenty wells in this area, were the source of fossil and lithologic samples studied. Changes in lithology in these cores compared with changes in mechanical log characteristics provided control for uncored wells.

The “Heath” Formation is composed of five laterally traceable, fairly distinct lithologic units—three shaly sequences separated by locally petroliferous sandstone units. An unconformity, indicated by a conglomeratic horizon, separates the lower two from the upper three units.

The fauna of the “Heath” Formation includes non-marine ostracodes, with which this study is primarily concerned, and non-marine pelecypods and syncarid crustaceans which occur in units intertonguing with strata containing marine brachiopods and pelecypods. Fossils occurring above the previously mentioned unconformity in the “Heath” indicate a Pennsylvanian Age for this portion of the unit. Plant fossils from the beds below the unconformity indicate a Mississippian Age for this lower portion of the “Heath”.

The possibility that this unconformity marks the Mississippian-Pennsylvanian boundary requires a more complete study of the fossils for confirmation. That portion of that “Heath” Formation above the unconformity in North Dakota is correlative with the Tyler Formation in Montana. Correlation of the lower portion of the “Heath” must await complete restudy of the fossils in the Tyler Formation of Montana.

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