Jacqueline C. Banks
Public Affairs Officer
Kaibab National Forest
928-635-8314
cell 928-606-7490
jcbanks@xxxxxxxxx
Well-Known Author Takes Geology Tour
of Kaibab National Forest
WILLIAMS, Ariz. – Well-known author
and geologist Wayne Ranney recently participated in a geology tour of the
Williams Ranger District of Kaibab National Forest. In fact, Ranney
helped lead the earth science discovery tour by teaming with Kaibab National
Forest geologist Jessica Lopez Pearce to explain geologic features at six
locations across the district.
The goal of the field trip was to provide
Forest Service resource specialists with a more in-depth understanding
of the geology of the local area – information that might prove valuable
when planning projects or doing field work.
The group started their tour at Summit
Mountain, which is located about 8 miles southeast of Williams. From
this high point, Ranney and Lopez Pearce explained the evolution of the
Colorado Plateau, Basin and Range, and the San Francisco Volcanic Field.
Ranney provided a description of the ancient Mogollon Highlands,
which once stood like an Andean-type mountain range across the southwestern
border of the Colorado Plateau approximately 100 million years ago. These
long-gone mountains have been replaced by the Arizona Transition Zone and
the Basin and Range Province, which are now visible in the area.
Kaibab National Forest resource specialists
expressed particular interest in the presence of local faults, like the
nearby Mesa Butte fault. Local faults like Mesa Butte are reminders
that there is always the possibility of an earthquake on the Williams Ranger
District.
Next, the group stopped along the southern
boundary of the Williams district in Grindstone Wash. Participants
observed the various sedimentary rock layers of the Coconino Plateau including
the Toroweap Formation, Coconino Sandstone, Hermit Formation, and Schnebly
Hill Formation. Ranney provided insight into the unique depositional
environments of each rock layer and showed beautiful illustrations of paleogeographic
reconstructions from a book he coauthored with Ron Blakey, titled Ancient
Landscapes of the Colorado Plateau.
The next stop was a sandstone quarry
near Ash Fork, at which tour participants discovered many fossilized reptile
tracks within the Coconino Sandstone. Ranney described how the Coconino
Sandstone was deposited in a 275-million-year-old desert environment containing
a large sand dune sea, or erg. A short drive through the sandstone
quarries provided participants an opportunity to see more three-dimensional
examples of the ancient sand dunes.
“It was fascinating to discover that
our beautiful pine forest was once a harsh desert complete with sand dunes,”
said Roger Joos, a Kaibab National Forest wildlife biologist. “And,
it was really awesome to understand the processes that created what are
now our flagstone quarries. The coolest part for me was to learn
exactly how the fossilized tracks that we often find in flagstone were
formed and preserved.”
As the tour headed south on Forest Road
6, participants were able to see volcanic features in the San Francisco
Volcanic Field including a dike, or vertical lava intrusion, and several
lava flows. The trip concluded with a stop at Johnson Crater, a geological
oddity, where Ranney and Lopez Pearce discussed the possible ways this
collapse structure was formed.
“I had no idea that we had so many
geological treasures out there,” said Mark Thibodeau, visitor information
specialist on the Williams Ranger District. “Now that I am more
educated, I can pass that information along to our visitors so that they
can enjoy the district even more and have a better experience during their
time here.”
