2 Zoology of Colorado 



truly said that we have witnessed the process of evolution from 

 the beginning, dull though our perception of it may have been. 



We who live in Colorado are exceptionally fortunate if we 

 desire to understand the past. Several years ago an eminent 

 geologist from Chicago was taken to the top of one of the Uni- 

 versity buildings. Looking about him, he remarked that it was 

 possible to see more geology from this spot than in the whole 

 state of Illinois. He referred to the variety of exposures, the 

 diversity of the rocks, the contrasts in the topography, the number 

 of different geological periods represented. When we travel over 

 the State we find even greater diversities and contrasts; so that, 

 for example, one familiar only with the front range seems to have 

 reached a new and unfamiliar world when he examines the mesas 

 and canons of the western part of the country. One who has 

 collected fossils in the numerous strata about Boulder, has an 

 entirely new set of plants and animals revealed to him if he digs 

 at Florissant or searches the rocks of the oil shale country. Not 

 only have wonderfully rich deposits of fossils been found, but 

 as yet the work of exploration is exceedingly incomplete, so that 

 the adventurous naturalist may still make discoveries of first 

 class importance. Indeed, it is not necessary to be a trained 

 naturalist in order to do this, though experience and judgment 

 count for much. 



The whole subject has taken on a new aspect in recent years, 

 consequent upon the study of radioactive minerals. Fifty years 

 ago there was an outstanding dispute between the biologists and 

 the physicists, represented especially by Professor Huxley and 

 Lord Kelvin, respectively. The biologists objected that the fifty 

 million years or thereabouts allowed by the physicists since the 

 earth became capable of supporting life was not sufficient for 

 evolution. It was necessary not only to account for the known 

 history of life, as revealed in the rocks, but perhaps for an equal or 

 longer period before this, to explain the relatively advanced state 

 of even the earliest well preserved organisms. For a long time 

 there seemed to be no solution, but now the physicists themselves 

 have discovered a whole new aspect of their science, and since the 

 rate of change in certain minerals is known, it becomes possible, 

 within rather wide limits, to estimate the actual age of sedimentary 

 rocks. The results are astonishing; the estimates of geological 



