Abstract

The Moenkopi formation of Triassic(?) and Triassic age is widely exposed in the salt anticline region in southeastern Utah and southwestern Colorado. The distribution of the Moenkopi is that of a blanket of irregular thickness with several large holes in it, due to nondeposition and pre-Chinle erosion. Four members of contrasting lithology have been mapped in the Moenkopi in the salt anticline region. In ascending order these members are: 1) the Tenderfoot member, composed dominantly of muddy or silty, poorly sorted sandstone; 2) the Ali Baba member, composed of interstratified arkosic conglomeratic sandstone and fissile siltstone; 3) the Sewemup member, composed dominantly of fissile siltstone with minor beds of conglomeratic sandstone and gypsum; and 4) the Pariott member composed of interstratified sandstone and siltstone. Part of the Tenderfoot member of the Moenkopi formation is correlative with the Hoskinnini member of the Moenkopi formation of southeastern Utah, a unit which may be either Permian or Early Triassic in age or possibly both. If equivalents of the type Moenkopi of northeastern Arizona are present in the salt anticline region they may include the upper part of the Sewemup member and part or all of the Pariott member.

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