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Click on the links below to see detailed descriptions of these maps. |
PLEASE USE THE USGS WEBSITE |
| The Oil and Gas Investigations Maps (OM) Series and Charts (OC) Series show the subsurface structure and stratigraphy and surface geology of selected oil and gas fields and of other areas having hydrocarbon potential. They may be black and white or multicolor. Most maps and charts have an explanatory text printed on the margin or in a separate pamphlet. Some are on multiple sheets. Sheet sizes and projections vary. Each map or chart is folded and placed in a paper jacket.multicolor. |  Part of "Structure Contours Map on top of the Middle Member of the Piper Formation of Middle Jurassic Age in the Williston Basin and Adjacent Areas in Montana, North Dakota, and South Dakota, "1959, 53 1/2 x 39 inches. |
| Maps. Each map is plotted on a topographic or planimetric base. Typically included are cross sections, columnar sections, correlation diagrams, and well logs. Maps numbered 1 to 109 in the series are designed preliminary; those from number 110 onward carry the prefix OM. Most maps in this series were published before 1965. | |
| Charts. Charts generally consist of well logs, correlation diagrams, graphs, and tables. Some charts include seismic data or maps. Charts numbered 1 to 39 in the series are considered preliminary; those from number 40 onward carry the prefix OC. | |