You have driven into a geologist’s paradise—the San
Rafael Swell. Here layers of the earth’s crust are eroded and
exposed for easy viewing, reveling millions of years of
earth’s history. You can identify each layer by its color and
characteristics. The dark velvety gray of the Mancos Shale to the
west are deposited in an ancient Cretaceous sea. The yellows and
golds of the Ferron and Dakota Sandstone tell of a time when this
area was a great seashore with a delta, where materials laden with
plant and animal life that eventually became a source for coal and
natural gas, were deposited. Then come the soft purple, green, and
red beds of the Morrison layer. When this layer was formed during
the Jurassic Period, the area had tropical forests, inhabited by
giant dinosaurs that dies and left behind their bones to intrigue
and enchant us. Ancient tidal flats created the many thin red
layers of the Summerville Formation that you see before you. The
view area itself is built on the beige-green Curtis Formation,
which was deposited in an ancient Jurassic sea. To the east, the
upward tilt of layers is an indication of the huge eroded anticline
that is the spectacular San Rafael Swell.
To log this cache as found, answer the following:
1. There are 5 eras identified by the sign, what are they?
2. Which of these eras is not exposed?
3. Which era is the San Rafael Knob part of?
4. Form the above photo, what are you seeing?
5. OPTIONAL: Post a photo of you or your team at this location.