PRE-MOENKOPI UNCONFORMITY OF COLORADO PLATEAU 6^ 



variable thickness of the Moenkopi itself. The following detailed 

 section was measured in this vicinity: 



SECTION NEAR MULE TWIST CANYON 



(4) 100 feet 



(3) 60 feet 



(2) 40 feet 



(i) 75 feet 



red and yellowish-gray sandy shale and some sandstone 



weU-bedded gray fossiliferous limestone 



regularly bedded calcareous sandstone 



massive cross-bedded gray sandstone, base not exposed 



The gray standstone and Hmestone are undoubtedly the Aubrey 

 group of the Carboniferous mentioned by Gilbert' in the Henry 



Fig. 2. — Cross-bedded Coconino(?) sandstone near Mule Twist Canyon, Water 

 Pocket Flexure, near Henry Mountains, Utah. 



Mountains. The limestones and upper bedded sandstones (mem- 

 bers 2 and 3) were sparingly fossiliferous, and several species were 

 collected, but the collection was unfortunately lost by the burning 

 of an ofi&ce building in which the writer was temporarily quartered. 

 The fauna was totally unfamihar to the writer, and consisted of 

 very small crinoid stems, several pelecypods, and one or two small 

 brachiopods. They did not resemble at all the faunas so abundant 

 in the Goodridge formation of the San Juan Oil Field, a formation 



' G. K. Gilbert, The Geology of the Henry Mountains, 1880. 



