부산대학교 도서관

A drilling program was conducted in western North Dakota by the North Dakota Geological Survey under a grant from the U.S. Geological Survey. The drilling was done as part of the U.S. Geological Survey's program to evaluate and classify mineral lands in the public domain. The purpose of the program was to gather data on the thickness, quality, extent, and recoverability of lignite beds and the lithologic characteristics of the coal-bearing unit, the Fort Union Formation (Paleocene), in western North Dakota. Geophysical logs, lists of lignite beds, and locations of the test holes are included. The descriptive terms, sand, silt, and clay, reported by the geologist, were modified to sandstone, siltstone, and claystone to conform to the U.S. Geological Survey's policy of using lithologic (rock-unit) terms for bedrock formations. A core sample was taken from one test hole and is currently being analyzed for proximate analyses, Btu/lb values, form of sulfur present, and trace elements. Chemical analyses are also being run on the ash. Samples were described as collected and no depth adjustments based on logs were made. The lists of lignite beds were made from the density logs.