182 GEOLOGICAL SURVEY OF THE TEKRITOEIES. 



From the summit of Berthoud's Pass, at a height of eleven thousand 

 eight hundred and sixteen feet, we can look northward along the line of 

 the main range, which gradually flexes around to the northwest, while 

 the little streams seem to flow through the rifts. The general appear- 

 ance of the western slope of this great range would indicate that it is a 

 huge anticlinal composed of a series of ranges on each side of a common 

 axis, and then smaller ranges ascend like steps to the central axis. The 

 western side of this ridge slopes gently, while the eastern side projects 

 over abruptly. This main range also forms a narrow dividing line, or 

 " water-divide," between the waters of the Atlantic and Pacific. I stood 

 where the waters of each side were only a few feet apart, and felt a real 

 joy in passing, down the western slope of the mountain by the side of a 

 pure crystal stream whose waters were hastening on to the great Pacific. 



All down the western slope is a great thickness of superficial material, 

 loose sand, decomposing feldspar, with partially worn rocks of all sizes. 

 This is due quite evidently to local influences, ice and water wearing- 

 down the sides of the mountains and depositing the material adhering 

 to the masses of ice along the slopes. 



The springs of water are very numerous, and the water seems to col- 

 lect in the thick grass and moss-covered earth, forming large bogs. It 

 is also interesting to watch the growth of a stream from its source, re- 

 ceiving in its way the waters of myriads of springs, until it becomes a 

 river too formidable to ford easily. The little stream which rises in the 

 pass we followed to the Park, where it is fifty yards wide, and contains 

 an abundance of fine trout. 



Tfie Middle Park is really made up of a number of smaller parks, 

 which are somewhat independent of each other. Each one may present 

 different geological formations. The little park on the south side, which 

 we first enter, is a very beautiful one. The grass is luxuriant, and the 

 timber excellent. None of the older sedimentary rocks were seen along 

 the flanks of the mountains, bat a recent tertiary deposit seemed to 

 cover the country. On the east side of Fraser Creek there is a long, 

 high ridge, which is cut by the stream in several places, formed of the 

 white and yellow sands and marls which mark the pliocene tertiary on 

 the east side of the mountain. I have no doubt that it is a formation 

 of the same kind as that of the Arkansas marls, and cotemx3oraneous 

 with it. 



Along this creek there are some massive walls of this formation, mostly 

 yellow marls, but some layers of sandstone. This ridge extends from 

 the mountains far northward, and is about two miles wide; and between 

 it and the immediate base of the mountains is situated a beautiful valley 

 of considerable width. 



The Middle Park is apparently a quaquaversal, surrounded by the lofty 

 snowy ranges ; and the lower ranges descending like steps to the valley 

 ^■rhich constitutes the true ])ark. The park does not appear to be more 

 than from ten to twenty miles v/ide from east to west, and from fifty to 

 sixty long from north to south. In this park also the ranges of moun- 

 tains so surround it that the slopes seem to form a sort of quaquaversal 

 inclining toward a common center. 



Viewed from Middle Park, Long's Peak, and the range immediately 

 connected with, has a rugged, saw-like edge, as if composed of eruptive 

 rocks, and ridge after ridge inclines from it in regular order. 



About ten miles north of our camp, in the first park, we come to low 

 ridges of massive red feldspathic granite, and parallel with these granite 

 ridges are a series of sedimentary beds, commencing with the brick-red 

 beds. The strike is nearly north and south, and the dip west. These 



