THE SHINAEUMP. 147 



owing to the gradual transition into the Vermilion Cliff series above. Dis- 

 regarding the doubtful horizons, the thickness along the Hurricane ledge is 

 not far from 1,300 feet, and somewhat less at Kanab ; and, in general, it 

 attenuates very slowly and gradually as we recede southeastward, though 

 it never sinks to small proportions anywhere within the limits of the Pla- 

 teau Country. Besides the transitional shales above, there are three sub- 

 divisions. Commencing at the base, they are as follows : 



1. Silico-argillaceous shales 450 to 650 feet. 



2. Belted, highly-colored arenaceous aud siliceous shales 400 to 500 feet. 



3. Brown sandstone 150 to 250 feet. 



The thickness of the transitional shales up to the base of the Vermilion 

 Cliff sandstone may be reckoned from 550 to 750 feet. Within these shales 

 there often appears a singular conglomerate. It consists of fragments of 

 silic-ified wood imbedded in a matrix of sand and gravel. Sometimes 

 trunks of trees of considerable size, thoroughly silicified, are found, to 

 which the Piute Indians have given the name ^^ Shindrump," meaning "the 

 weapons of Shinav," the wolf-god. The conglomerate is found in many 

 widely-separated localities, with a thickness rarely exceeding 50 feet. It 

 occasionally thins out and disappears, but usually recurs if the outcrop be 

 traced onwards, resembling the mode of occurrence common to the coal- 

 seams of the Carboniferous coal measures. It is the most variable member 

 of the ShinArump thus far observed. It is found on the west flunk of the 

 Markagunt and throughout the great circuit of cliffs south of the High Pla- 

 teaus ; it is seen at Paria, and again at the Red Gate between the Aqua- 

 rius and Thousand Lake Mountain, the characters of the formation being 

 quite the same in all tliese localities. The conditions imder which it was 

 accumulated would seem to have been remarkably uniform, and may have 

 been similar in some respects to those attending the formation of coal. The 

 subsequent silicification of the wood upon a scale so extensive and even 

 universal is certainly a very striking phenomenon, and one for which no 

 explanation suggests itself. It may be of interest to mention that at Leeds, 

 in Southwestern Utali, the fragments of silicified wood were found to be 

 strongly impregnated with horn-silver. Subsequent prospecting, which had 

 been stimulated by this curious discovery, led to the finding of horn-silver 



