Geology and Mineralogy. 69 



The primary triangulation party was placed in charge of A. D. 



Wilson and took the field from Trinidad, the southern terminus 

 of the Denver and Rio Grande Railway, August isth, making 

 the first station on Fisher's Peak. From this point the party 

 marched by the valley of the Purgatoire, crossed the Sangre d'e 

 Christo range byway of Costillia Pass, followed the west base oi' the 

 range northward as far as Fort Carland, making ., Nation on 



tne west, called Blanea Peak, the principal summit of the Sierra 



Blanea group. This was ascended by the party under Mr. Wii-on, 



and found to be the highest peak in Colorado and the second 



peak in height in the Hinted States. A comparison with some of 



the first class peaks in Colorado will show the relative heights. 



Blanea Peak above sea level, 14,404 feet. 



Mt. Harvard " " 14,as4 " 



Cray's Peak " " 14,841 " 



Mt Lincoln " " 14,296 " 



Mt. Wilson " " 14,280 " 



Long's Peak " " 14,271 " 



Uncompahgre Peak " " 14,235 " 



Pike's Peak " " 14,146 " 



Mr. Wilson made eleven primary stations over a large portion 



of Southern and Western Colorado and completed about 1,000 



square miles of topography that had been omitted by one of the 



parties of last year. 



In compai ii"ii [.arty. Mr. Holmes made a 



hurried trip "through Colorado, touching also portions of New 

 Mexico and Utah. He was unable to pay much attention to 

 detailed work, but had an excellent opportunity of taking a gen- 

 eral view of the two great plain belts that lie, the one alon; tin- 

 east, the other along the west base of the Hocky Mountains. 

 For nearly 2,on0 miles travel he had constantly in view the Cre- 

 taceous and Tertiary formations, among which are involved some 

 of the most interesting geological questions. He observed among 

 other things tie _,, • persist. . of rl ■> gi ups ot locks 



throughout the east, wot ml north, ml .-] Ii\ in the west ; 



that from Northern New Mexico to Southern Wyoming the 

 various members of the Cretaceous lie in almost unbroken belts, 

 while the Tertiaries are hardly less easily followed. 



Between the east and the west there is only one great incon- 

 gruity. Along the east base of the mountains the upper < re- 

 taceous rocks,' including Nos. 4 and 5, are almost wanting and 

 consisting o "I leer of shales and laminated 



sandstones. Along t! ; . hevoines a promim-iit 



and import.) feature. In 



the " Mesa Verde" and the cap of 

 the Dolores plateau, it comprises upward of 2,000 feet of coal- 

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