Underground Stratigraphy of Montana

The purpose of this thesis is to study the subsurface stratigraphy of the state of Montana from information acquired from well logs, composite logs, and measured sections. Underground stratigraphy is important for the intelligent prospecting for oil, gas, or water. A knowledge of the strata beneath us can be gathered only by measurements of numerous outcrops or by deep drilling with careful sampling or logging of the formations passed through.

Stratigraphy and Paleontology of the Eagle Formation in Montana and Adjacent Areas

A conspicuous two hundred and fifty foot sandstone of central Montana, known as the Eagle Formation, constitutes part of the some five thousand feet of Cretaceous sediments in the state. It stands out in steep cliffs which stretch for many miles in the outcrop area from Wyoming to Canada.

The Geology of Lost Creek Canyon with Special Reference to Igneous Activity

This investigation was undertaken primarily as a problem in geologic mapping, coupled with a study of stratigraphy, glaciation, igneous phenomena, and structure. The area is admirably suited to a study of geology and geologic events. Because it is small in extent, the area was studied in some detail during the time which was devoted to field work. The record of igneous activity of past geological ages is re­markably well exposed, since Lost Creek Canyon was carved through the roof of a stock or batholith by the glaciers of the Pleistocene epoch.

Areal Geology of the Post-Paleozoic Surface of the Northwest Plains

Probably most of the area included in this report has been ex­amined to some extent by oil geologists, and most, if not all, of the important domes have been discovered and surveyed thoroughly. In parts of the area, the bedrock is covered by glacial drift or alluvium materi­al, but it is reasonable to believe that no new domal structure will be found. This means that surface examination alone will be insufficient in locating new oil fields, so future prospecting will be dependent, to a great extent, on studies of sub-surface stratigraphy.

Insoluble Residues of the Lower Mississippian Limestones of the Madison Group

The correlation of non-fossiliferous drill samples is one of the difficult problems that is en­countered in sub-surface stratigraphy. In order to truly correlate a formation, it must have some dis tinctive features and have an areal persistence of these features. These requirements are probably met best by limestone.

Layer-cake, anoxia, and other myths: A new look at the Devonian-Mississippian Bakken Formation Reservoir, Williston Basin, North Dakota

The Upper Devonian-Mississippian Bakken Formation in the Williston Basin is one of the most prolific onshore petroleum systems in the continental U.S., consisting of a middle carbonate-siliciclastic member sandwiched between two organic-rich units, the Lower and Upper Bakken shales. Dr. Egenhoff discusses the formation’s surprising departures from standard stratigraphy models and depositional models which contribute to its unique characteristics.

Geology of the Lost Creek-Modesty Creek Area Deerlodge County, Montana

In 1915 the United States Geological Survey published a folio by Calkins and Emmons on the geology of the Philipsburg Quadrangle, which ad­joins the area now under study to the west. Geology of this portion of Montana had not been mapped previously; consequently the purpose of this thesis is to make a geological reconnais­sance of the stratigraphy and structure of the area.

Geology of Smoke Hollow Area 8 Miles Southeast of Deerlodge, Powell County, Montana

This investigation was undertaken primarily as a problem in geologic mapping. The stratigraphy was studied as to the character, age, and sequence of the geologic formations that are exposed. The conclusions were based principally on the field relationships and lithology because no fossils were found.