LIST OF HELIOTYPES. 



Heliotype I.— The Gate of Monroe. 



This picture represents the narrow gorge through which the drainage of the Monroe Amphitheater 

 passes to join the Sevier River. It is situated in the western wall of the Sevier Plateau, near its loftiest 

 part. The gorge is cut in a large mass of hornblendic propylite, and forms a cleft about 20 feet wide 

 and nearly 400 feet deep. In the background is seen one of the large hills within the amphitheater, 

 composed of trachyte and augitic andesite. 



Heliotype II. — Conglomerate in the Tushar. 



The cliff here exhibited is upon the eastern flank of the Tushar facing Circle Valley. In the face 

 of tho cliff are seen about 1,300 feet of conglomerate surmounted by 400 feet of lava. The bedding here 

 is much less conspicuous than is usually the case in such formations. 



Heliotype III. — Tufa. — Markagunt Plateau. 



This material has been derived from the complete decay of lavas, and consists of aluminous 

 silicate, accumulated as a deposit in the bed of a small lake, where it was consolidated and subse- 

 quently eroded. Such formations are not very uncommon on the Markagunt and elsewhere. 



Heliotype IV. — Volcanic alluvial conglomerate on trachyte.— Panquitch Canon. 



The beds here exhibited were derived from the break-up of older volcanic masses situated in the 

 vicinity. At a former epoch the river flowed at a level as high as the summit of the canon wall, aud the 

 upper portion of the conglomerate was eroded. An uplifting of the locality subsequently took place, 

 and the river cut its caiion, exposing the structure of the beds. It will be noted that the layers pre- 

 sent an arrangement suggestive of false stratiOcation or cross-bedding, since their planes of stratifica- 

 tion do not conform to the surfaco of tho trachyte below. This is tho normal structure of all alluvial 

 cones. 



Heliotype V. — Metamorphosed tufas. — East Fork Canon. 



The beds here seen arc all water-laid and occur within the inner gorge of the cauon. The upper 

 member exhibited is a massive rock, with all the lithologic characters of an intrusive igneous rock. 

 Some of the thin layers below have the same character. (See Chap. XI.) 



Heliotype VI.— Tufa and conglomerate. — East Fork Canon. 



On the right are sesn the continuations of the same beds as in the preceding illustration. The 

 hill in the distance is composed of tho same rocks below with coarse volcanic conglomerate above. 



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