Laserfiche WebLink
~.. <br />ATTACHM1tEIVT 6 <br />GEOLOGIC SUMMARY <br />The sedementary section, from which the cores of the Craig Coal Area <br />were taken, consists of a series of shales, siltstones, sandstones and <br />coals deposited in a marine environment, alternating between brackish- <br />water and fresh-water. The more persistent sandstones were deposited <br />on beaches or in shallow water near a large body of water. See reference. <br />The entire Craig Coal Area is expressed topographically as a north dip <br />slope of 10 to l~ degrees, with some minor variations. A few strike faults <br />can be identified. <br />-~ <br />Most siltstones and sandstones are shades of gray, contain a calcareous <br />cementing agent and are fairly soft. A few siltstones are hard, a very few <br />are extremely hard and probably contain siliceous cement. The sandstones <br />are lighter gray than the siltstones and are mostly fine grained. Most <br />are slightly calcareous and in general soft. Shales are generally gray to <br />dark gray, some are calcareous and soft. A few fossil shell fragments <br />were found in the darker shales. Black, carbonaceous shales are commonly <br />associated with coal seams, though usually as a minor constituent. The <br />coals contain very little in the way of obvious impurities, from cursory <br />inspection. These coal impurities usually consist of thin black shales or <br />• very thin gray siltstones and thin, hard impure coal streaks which, when <br />~~ <br />54 <br />