'8 A'AA^SAS CITY REVIEW OF SCIENCE. 



the Granite Hills its rocks seem to have been sufficiently modified by heat to ac- 

 quire an obscure columnar structure, thus opening lines of weakness, which have 

 been sought out by the water, aided by insinuating roots and the power of frost, 

 until one columnar mass after another has been pried off and finally removed by 

 the further action of the elements. This process results in a deep and narrow 

 valley known as a canon. 



Hundreds of canons are found in various parts of the Rocky Mountain re- 

 gion, some of which are of enormous dimensions. But those visited by me lie 

 along the course of Fountain Creek, at the base of Pike's Peak, and are interest- 

 ing aside from their wonderful scenery, because affording such an excellent oppor- 

 tunity to examine not less than 4,000 feet of sedimentary rocks. In many of 

 them the torrent had plowed down into the underlying feldspathic granite, giving 

 an amazing exhibition of aqueous energy. 



Williams' Canon, near Manitou, was the last one visited, and on some ac- 

 counts, I found it the most interesting of all. 



The mouth of this canon is cut through the red sandstone to a limestone, at 

 first yellowish and sandy, but improving in quality as one goes deeper into the 

 gorge, until it is of a good quality for all purposes to which limestone is ordinari- 

 ly put, and large quarries have been opened, to which a wagon road leads. 



The walls rise for 400 or 500 feet on each side, in many places absolutelj 

 perpendicular, and sometimes so close to each other that both wheels of the limt 

 carts graze the walls in passing. 



I found but few fossils, and they seemed to belong to the Silurian formation ; 

 a conclusion verified by Hayden's report, which speaks of these beds as being 

 decidedly referable to the Silurian group. Prof. Hayden adds : "I have never 

 known of any Carboniferous fossils being found here, but am confident that there 

 are 1,000 to 1,500 feet of these beds between the Silurian and Triassic." 



On his geological map, 1876, he assigns a portion of these rocks to the Car- 

 boniferous, and also marks high ridges of Silurian limstones on the side of the 

 mountain about four miles north. 



The existence of heavy deposits of nearly homogeneous limestone under cir- 

 cumstances so favorable for excavation, excited my curiosity as to the existence 

 of caves in that locality. But after following the canon for two miles or more, 

 toward its head, nothing of the sort presented itself, except an open gorge, to 

 which visitors had given the name of " The Cave of the Winds." 



An entrance was discovered, last June, through this very gorge to a cavern of 

 large dimensions, named for the boys who found it, Pickett" s Cave, and described 

 by Rev. R. T. Cross in the Congregational Nezvs for March, 1881. 



Some progress in underground research was made last fall by an organization 

 known as " The Boys' Exploring Association," of which the young Picketts are 

 members. "They found numerous obstructions, but noticed in one of the rooms 

 entered a peculiar chimney-like aperture nearly closed by dripstone. 



Through this chimney a passage was forced, last January, by Messrs, Rein- 

 hart & Snyder, who now own the cave. They found at its upper end a spacious 



