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.~ <br />u <br /> <br />~~ Cretaceous' <br />The Mancos Formation is the principal stratigraphic unit exposed <br />in this area, The Mancos Shale is composed largely of gray to <br />black marine shale, parts of which are calcareous, a few beds of <br />lenticular sandstone, a very few beds of limestone, and thin beds <br />of bentonite. In addition, it contains two members in its lower <br />part: the Frontier Sandstone Member and the Mowry Member near <br />the base. The Atancos ranges in thickness from 3,900 feet to 5,520 <br />feet. Fractured zones from this shale produce oil and gas in several <br />fields. <br />The Dakota Sandstone underlies the Mancos and consists of massive, <br />friable, commonly non-calcareous, fine grained sandstone, containing <br />lenses of medium to coarse grained, rounded frosted grains. Thick- <br />ness ranges from 40 to 80 feet. There are frequent shows and some <br />production of oil and gas in this formation. <br />The hforrison Formation consists of predominantly variegated shale, <br />some thin beds of limestone, local lenses of chert conglomerate <br />and in the lower one-third, massive beds of sandstone. The for- <br />mation is an oil and gas producer. <br />Older rock types are present at depth beneath the subject land, but <br />are insignificant in relation to the mineral values of the subject <br />application, <br />