LIST OF HELIOTYPES. 



Heliotype I. — The Gate of Monroe. 



This picture represents the narrow gorge throngh 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 augitio andcsite. 



Heliotype II. — 'Conglomerate in the Tushak. 



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

 of the 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 Markugunt and elsewhere. 



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



The beds hero exhibited wore derived from the break-up of older volcauic masses situated in the 

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

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

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

 sent an arrangement suggestive of i'alse stratification or cross-bedding, since their planes of stratilica- 

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

 cones. 



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



Tlie beds here seen arc all water-laid and occur within the inner gorge of the cafion. 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 CaSon. 



On the right are sesn the contiiinatious of the same bcids as in the preceding illustration. The 

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



