Cenozoic Quaternary Recent
Pleistocene
Tertiary Pliocene
Miocene
Oligocene
Eocene
Paleocene
Mesozoic Cretaceous
Jurassic
Triassic
Paleozoic Permian
Pennsylvanian
Mississippian
Devonian
Silurian[1]
Ordovician
Cambrian
— Precambrian
[1]_The Silurian is the only major subdivision of the stratigraphic time
scale not represented in Grand Teton National Park._
We are immediately struck by the fact that all of the subdivisions of
the stratigraphic time scale since the beginning of the Paleozoic are
compressed into the last 5 inches of our yardstick! All of the other 31
inches represent Precambrian time. We also see that subdivisions of the
stratigraphic time scale do not represent equal numbers of years. We use
smaller and smaller subdivisions as we approach the present. (Notice the
subdivisions of the Tertiary and Quaternary in table 1 that are too
small to show even in the enlarged part of figure 19). This is because
the record of earth history is more vague and incomplete the farther
back in time we go. In effect, we are very nearsighted in our view of
time. This “geological myopia” becomes increasingly evident throughout
the remainder of this booklet.
[Illustration: Figure 19. _The geologic time scale—our yardstick in
time._]