LOCALITIES WHERE TERTIARY INSECTS HAVE BEEN FOUND IN AMERICA. 



Florissant, Colorado. — The Tertiary lake basin at Florissant,' already 

 famous for its proliiic beds of plants and insects, is situated in a narrow 

 valley high up in the mountains at the southern extremity of the Front 

 Range of Colorado, at no great distance from Pike's Peak. 



The basin is shown on Sheet 13 of the geological atlas of Colorado, 

 published by Dr. Hayden's survey, and its outlines are marked with con- 

 siderable accuracy, although upon a comparatively small scale. The 

 ancient lake lies in the valley of the present South Fork of Twin Creek, 

 and of the upper half of the main stream of the same after the South Fork 

 has joined it. Following the old stage road from South Park to Colorado 

 Springs, and leaving it just above the railway station at Florissant, and 

 then taking tiae road which leads over the divide toward Canon City, we 

 pass between the Platte River and the x\rkansas divide, through the entire 

 length of the basin. This road crosses the South Platte a short distance, 

 say a kilometer and a half, below the mouth of Twin Creek, climbs a long 

 gradual slope on the east bank of the river to an open grassy glade about 

 2,500 meters above the sea, and then descends a little more than three kilo- 

 meters from the river to join the valley of Twin Creek. One scarcely 

 begins the descent before his attention is attracted by the outcropping of 

 drab-colored shales, which continue until almost the very summit of the 

 divide is reached and the descent toward the Arkansas besfun, a traveling 

 distance of not far from 13 kilometers. The shales may indeed be seen for 

 several kilometers on the farther side of this divide, but no organic remains 

 have yet been found in them. 



By climbing a neighboring peak, thrice baptized as Crystal Mountain, 

 Topaz Butte, and Cheops Pyramid, and known to the old miners as Slim 

 Jim, we obtained an admirable bird's-eye view of the ancient lake and the 



' This account of Florissaut is taken almost bodily from a paper by Prof. Arthur Lakes and 

 myself (Bull. U. S. Geol. Siirv. Terr., vol. 6, 1881, pp. 279, seq.). 



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 VOL XIII 2 



