Geological Aspects of Evolution 105 
valuable in that it affords another method on which may be based 
estimates of the age of the deposits of older fossil man. 
In conclusion, the geologic record supports the doctrine of 
evolution, in that it reveals the appearance of progressively higher 
types of life with advancing time, but the origin of the earth, of 
life, and the earliest stages of man’s existence are enveloped in 
mystery. 
