146 UNIVERSITY OF COLORADO STUDIES 



mountain valley, and are underlaid by granite and completely isolated 

 from all other sedimentaries by several miles of crystalline rocks, strati- 

 graphy can throw no light whatever upon the subject. Any deforma- 

 tion which may have occurred in the valley would be difficult to locate 

 or to follow at all through the granitic complex, even if it extended 

 to rocks of known age, so that no help could reasonably be expected 

 from that source. The presence of masses of rhyoHte along and near 

 the margins of the ancient lake is of no assistance, because of the impos- 

 sibihty of determining their age exactly in the crystalhne mass, and 

 the character of the materials composing the lake beds themselves 

 is wholly valueless as evidence of age, as similar materials might have 

 been available at periods long prior and subsequent to the lake period. 



The fossils have been considered indicative of a much milder cli- 

 mate than that which now prevails in the region. It has been stated 

 that the fossil flora and fauna of the vicinity are in a general way simi- 

 lar to the present-day flora and fauna of the Gulf states, though speci- 

 fically, and to a considerable extent generically, distinct. Scudder 

 has shown that, while the fossil insect fauna exhibits distinct tropical 

 affinities, there is also a very definite relation to the present insect 

 fauna of the region. The latter relation applies also to the fossil and 

 recent flora. The fluctuation in cHmate since Eocene time has been 

 much greater than indicated by the difference in plant and animal 

 life as shown by the fossils of Florissant. The glacial epoch has inter- 

 vened, during which time, although glaciers apparently did not actu- 

 ally reach this valley, they were in such close proximity and so extensive 

 through the higher mountains that the chmate was probably consid- 

 erably colder than now, and differed in other respects, such as pre- 

 cipitation, relative humidity, etc., from that of either Tertiary time 

 or the present day. 



Many giant fossil Sequoia stumps and logs are found in the southern 

 part of the lake basin. These have been visited by hundreds of tourists, 

 and large quantities of the "petrified wood" have been carried away 

 by reHc-hunters. Several years ago an effort was made to cut the 

 largest stump into three or four sections for transportation and exhi- 

 bition, but the attempt met with failure, and portions of the broken 



