This earthcache requires visiting two locations along the
north rim of the Grand Canyon of Yellowstone, one stop at
Inspiration Point and the other at either the Upper or Lower
Falls. Alternative locations on the south rim approximately
that are approximately opposite the provided coordinates would
also provide similar experiences. However at the time of my
visit, the south rim was closed for construction. The terrain
can be taken down to a 1 by staying at the lookout parking
lots.
Inspiration Point N44 43.478 W110 28.189 (the coordinates are
out on the point. Cachers that have difficulty with stairs can
remain in the parking lot) The giant Yellowstone Caldera was formed
about 640,000 years ago (see Yellowstone Caldera at Madison
Junction). The area around Canyon was later filled with thousands
of feet of rhyolite, a viscous gaseous volcanic rock about 480,000
years ago.
Hydrothermal activity that is so common in Yellowstone
chemically changed areas of the rhyolite. Hydrothermal activity can
still be seen in some parts of the canyon. This alteration gave the
walls their spectacular colors and weakened the rocks.
At one time glaciers covered the area under a thick blanket of
ice. About 14,000 years ago the glaciers began to melt, sending
large volumes of water down the canyon. These waters quickly eroded
down through the hydrothermally weakened rocks.
Upper or Lower Falls N44 42.785 W110 29.982 or N44 43.095 W110
29.777 (again cachers that have difficulty with stairs or steep
trails can stay in the parking areas) However, the rhyolite was not
altered along the entire length of the canyon. Where the rhyolite
remained unaltered it is much stronger. At these points, falls
formed because the altered rhyolite down-stream of the unaltered
rhyolite eroded down much faster.
Logging requirements:
Send me a note with :
- The text "GC14G6F Grand Canyon of Yellowstone" on the first
line
- The number of people in your group.
- send me a note with the differences you see in the rhyolite
along the sides of the canyon at each of the stops. You can stick
to color differences, angles of the canyon walls, apparent cohesion
(STAY ON THE TRAIL, OBEY ALL WARNING SIGNS, AND DO NOT DO
DESTRUCTIVE TESTING)
- See if you can find some altered rhyolite between the upper and
lower falls to account for the two falls.
The above information was compiled from the
following sources:
- Fritz, William J., Roadside Geology of the
Yellowstone Country, Mountain Press Publishing Company, May
1989.
- Canyon Area Trail Guide, Yellowstone National
Park, Yellowstone Association, April 2007
Placement approved by the
Yellowstone National Park