One of geology’s greatest philosophical contributions has been the
demonstration of the enormity of geologic time. Astronomers deal with
distances so great that they are almost beyond understanding; nuclear
physicists study objects so small that we can hardly imagine them.
Similarly, the geologist is concerned with spans of time so immense that
they are scarcely comprehensible. Geology is a science of time as well
as rocks, and in our geologic story of the Teton region we must refer
frequently to the geologic time scale, the yardstick by which we measure
the vast reaches of time in earth history.