A. L. Kroeber,
Anthropology
(1923)
“ Just as the geologist knows that one fossil is older or younger than another from its position in the earth’s crust or the stratum in which it was laid down, so the student of the beginnings of human civilization knows that the deposit at the bottom of a cave must be more ancient than the refuse at the top. He calls in the geologist to tell him the age of a glacial deposit or of a river terrace, and thus he may learn that, of two types of implements found at different places or levels, one is so many thousands of years or geological periods older than the other. ”

