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130' , and is fine-to-medium-grained , quartzitic to feldspathic , <br /> poorly to moderately sorted , with a clay matrix at the top . <br /> Directly above the Middle Sandstone is a <br /> coaiy, black to gray, sandy siltstone , of up to 13 ' thick- <br /> ness , which merges into the overlieing coal seam, known as <br /> the Middle Bed. The coal seam ranges from 5 ' to 20 ' in <br /> thickness , and is mined from the No . 2 mine entry . Approx- <br /> imately 1 million tons have been mined from the Middle bed . <br /> The overlieing sequence occurs in the Upper <br /> Shale Submember of the Bowie . It consists of mudstone , <br /> sandstone and shale and is around 200 ' thick. <br /> The Upper Sandstone is up to 100 ' thick and <br /> is virtually identical to the Middle and Rollins sandstone <br /> beds , except that grain size is somewhat coarser . <br /> The Paonia Shale Member overlies the Upper <br /> Sandstone . It consists of lower and upper deltaic plain <br /> coal beds , including the Placita and Sunshine seams , shales , <br /> siltstones and sandstone . The upper boundary of the Paonia <br /> is indistinct , merging into the undifferentiated Williams <br /> Fork where sandstone becomes the predominant rock type . <br /> The Placita coal seam lies at the base of the <br /> Paonia Shale Member , just above the Upper Sandstone . It is <br /> of 3 ' to 6 . 8 ' thickness , and is generally too thin and <br /> irregular for mining . <br /> Approximately 50 ' -60 ' above the Placita , a <br /> thin bed of coal , probably the Sunshine Seam, occurs . It is <br /> 12 <br />