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The Ashern Formation (Middle Devonian) In The Williston Basin, North Dakota, Frederick K. Lobdell

Theses and Dissertations

The Ashern Formation (Middle Devonian) is the basal unit of the Kaskaskia Sequence in North Dakota. It unconformably overlies the Interlake Formation (Silurian) and underlies, probably paraconformably, the Winnipegosis Formation (Middle Devonian). The Ashern is present in the northwestern one-half of the state, and attains a maximum thickness of 180 feet (55 meters) The Ashern Formation may be subdivided into a lower red member and an upper gray member. The latter directly overlies the Interlake Formation where the red member is absent. Both members are argillaceous, microcrystalline dolostones containing minor quartz silt. Anhydrite, present in both members, is much more …