The rugged grandeur of the Tetons is a product of four geologic factors:
the tough hard rocks in the core, the amount of vertical uplift, the
recency of the mountain-making movement, and the dynamic forces of
destruction. Many other mountains in Wyoming have just as hard rocks in
their cores and an equally great amount of vertical uplift, but they
rose 50 to 60 million years ago and have been worn down by erosion from
that time on. The Tetons, on the other hand, are the youngest range in
Wyoming, less than 10 million years old, and have not had time to be so
deeply eroded.