Laserfiche WebLink
• seams within this group is called the Dry Creek coal bed and is situated about 400 feet <br />above the iwentymite sends [one member, <br />The Lewis shale conformably overlies the Meseverde Group end, like the upper unit of the <br />YiLliams Fork Formation, is highly variable in thickness. It is principally a homogenous <br />marine shale. I[ tends to be more sandy in the upper portion of the formation and may <br />contain a few lenticular sandstone Layers (Figure 2). <br />The youngest Cretaceous rock formation exposed in the area is the Lance Formation (Figure <br />1). It conformably overlies the Lewis shale and is about 1,000 to 1,500 feet thick- The <br />Lance Formation is comprised of interbedded shale, sandy shale, sandstone, and coal. Some <br />of the sandstone layers can be rather thick (about 100 feet). The only coal bed present <br />in the Lance Formation which is of any economic significance is the Kimberly coal bed <br />rhich has been found to be as thick as 14 feet in some areas (Bass et al., 1955). <br />The Fort Union Formation of Tertiary age lies above the Lance Formation. It consists of <br />interbedded sandstone, shales, and coals deposited during the Paleocene epoch and is <br />• approximately 1,400 feet thick (Bass et al., 1955). Compared to the Lance Formation, the <br />sandstones are coarser, the shales ere lighter gray in color, and there are more coal <br />layers. The thickest regional coal seem present in [he Fort Union Formation is the <br />Seymour Coal. <br />The Yasa[ch Formation of Eocene age unconformably overlies the Fort Union Formation. It <br />is comprised primarily of fresh water stream-laid sandstone and shale deposits. <br />Unconsolidafetl alluvial, terrace, and surf icial deposits of aueternery age overlie the <br />exposed geologic formations in some areas, particularly along larger streams. <br />Sife Soecif is Geolouv <br />For a period of more than ZO years, Peabody Coal Company has gathered and analyzed <br />detailed information on the geology of the Seneca Il and Seneca II-Y Xines located 4 miles <br />northeast and 3.5 miles west, respectively, of the Yoast permit area. This information <br />includes a program of high density exploration drilling, geologic mapping, topographic <br />mapping, aerial photography, field investigations, and ground water quantity and quality <br />date. ~ comprehensive description and analysis of this information, in addition to <br />. site specific Yoast data, will provide background information for ground water and surface <br />5 <br />