Colorado A Million Years Ago 



By T. D. A. COCKERELL 



Professor of Zoology, University of Colorado 



NO one pretends tliiit estimates of 

 geological time are even ap- 

 proximately exact; yet they are 

 not pure guesswork. Converging evi- 

 dence, derived from many different 

 sources, leads us to the belief that we 

 can, in a very rough and general way, 

 calculate the passage of time represented 

 by the different strata. It is not im- 

 possible that, in the future, our knowl- 

 edge will become relatively precise, but 

 for the present we may assume that the 

 Florissant fossil beds are a million years 

 old, more or less. Such an assumption, 

 even if correct, is perhaps not particu- 

 larly illuminating, for few of us have 

 had to do with a million of anything. 

 Perhaps the easiest way to think of it is 

 to note that it represents five hundred 

 times the distance of time between us, 

 and the time of Christ. If one mile is 

 taken as the equivalent of the passage of 

 time since the birth of Christ, then five 

 hundred miles will take us back to Lake 

 Florissant and its Miocene life. The 

 estimate of a million years is certainly 

 not too great; the error is probably on 

 the side of moderation. 



Important disco\eries do not always 

 present dramatic elements until seen in 

 the light of subsequent events. Dr. 

 A. C. Peale, in the early seventies of the 

 last century, accompanied a party of the 

 United States Geological Survey which 

 camped one eAening in a mountain 

 valley west of Pike's Peak. While 

 supper was being prepared, Peale wan- 

 dered around examining the rocks, and 

 soon came upon well-preserved fossil 

 leaves. This was the actual discovery 

 of the Florissant shales. I did my best 



to get Dr. Peale to write out in detail 

 his recollections of the occasion, but he 

 never did so. This unexpected discov- 

 ery of Tertiary fossils in the midst of a 

 granite region interested naturalists, 

 especially when it appeared that not only 

 were beautifully preserved leaves to be 

 obtained, but also numerous fossil in- 

 sects, together with fishes and even birds. 



In 1877, Dr. S. H. Scudder, then the 

 greatest authority on fossil insects, 

 spent the summer at Florissant, and 

 obtained a very large collection. The 

 beds proved so rich that many were 

 attracted to them, and the total number 

 of specimens secured mounted to many 

 thousands. Great volumes were even- 

 tually published by the United States 

 Geological Survey, in which Scudder 

 described the insects and Lesquereux 

 the plants, while Cope made the fishes 

 known, in connection with other studies 

 of Tertiary vertebrates. 



Lesquereux died, and Scudder was 

 stricken with paralysis before he had 

 completed his labors. For a long time 

 Florissant was neglected, except for 

 occasional ^•isits by tourists who gath- 

 ered small collections of fossils. It is 

 probable that during this period the 

 total number of specimens taken away 

 was not inconsiderable, but they were 

 scattered about the country and re- 

 cei\ed little scientific attention. The 

 Hambach collection, now in the United 

 States National Museum, was the basis 

 of a paper on the fossil plants by Mr. 

 W. C. G. Kirchner. A rather large 

 collection exists in the Natural History 

 Museum at Denver, but for the most 

 part it remains unstudied. The Prince- 



443 



