The visitor who looks at the high, rugged peaks of the Teton Range is
seeing rocks that record about seven-eighths of all geologic time. These
Precambrian rocks are part of the very foundation of the continent and
are therefore commonly referred to by geologists as basement rocks. In
attempting to decipher their origin and history we peer backward through
the dim mists of time, piecing together scattered clues to events that
occurred billions of years ago, perhaps during the very birth of the
North American Continent. To cite an oft-quoted example, it is as though
we were attempting to read the history of an ancient and long-forgotten
civilization from the scattered unnumbered pages of a torn manuscript,
written in a language that we only partially understand.