ROCKY MOUNTAIN A Guide to the Geology of Rocky Mountain National Park, Colorado

WITH THE foregoing brief outline of geology we are now in position to examine with greater interest the park which is the object of our study.

The oldest rocks of this region are dark schists which carry innumerable sparkling flakes of black mica. At one time these rocks must have been deeply buried within the earth for they have been so changed by heat and pressure that their original nature is not easily determined. They represent the sediments of an ocean which covered this region almost a billion years ago, a time so vast that the human mind fails in comprehension of it.

Judging from exposures along Thompson Canyon on the Loveland Road, these beds are thousands of feet in thickness. In their formation enormous amounts of rock were eroded from some ancient land by streams and piled layer upon layer on a sea floor which sank slowly as the weight upon it increased. In that remote period there was no plant life upon the land to protect it against the fury of the floods, and erosion and deposition were probably more rapid than they are today. The beds which are now at the surface were thus buried by overlying sediments at depths of thousands of feet. Since their burial erosion has removed the sediments which once covered them, thus exposing them to view.