“Time, geologic time, looks out at us from the rocks as no other objects in the landscape. Geologic time! How the striking of the great clock, whose hours are millions of years, reverberates out of the abyss of the past! Mountains fall and the foundations of the earth shift as it beats out the moments of terrestrial history. Rocks have literally come down to us from a foreworld. The youth of the earth is in the soil and in the trees and verdure that spring from it. Its age is in the rocks