rocks called Bright Angel Shale underlie much of the
trail network in the Grand Canyon.
CANYON, Ariz. ó When I first peered into the layer cake
that is the Grand Canyon several years ago, I was
surprised to spot a continuous strip of green between a
grayish section and a red-brown one. "How could so
much shrubbery grow in the desert Southwest?" I
wondered as I stood at the edge of the South Rim.
wasnít until I revisited the Grand Canyon in October of
this year that I discovered my error. Walking in that
green layer, I saw a fair amount of plant life, but it was
actually a green rock called Bright Angel Shale that gave
this strata its distinctive hue.
Tonto Trail lies just above the Inner Gorge, a collection
of rocks that is considered the "basement" of
the Grand Canyon. Green-colored rocks called Bright Angel
Shale underlie much of the trail network in the Grand
Canyon. More than anything else, the Grand Canyon is a
product of the Colorado River, which through water and
sediment has sculpted the canyonís walls. The Monument
stands in a creek with the same name. Monument Creek is in
one of the many beautiful side canyons in the Grand
Canyon, the jewel of northwestern Arizona. The view from
the Tonto Trail, which parallels the Colorado River in the
Grand Canyon. The Tonto Trail lies just above the Inner
Gorge, a collection of rocks that is considered the
"basement" of the Grand Canyon. Green-colored
rocks called Bright Angel Shale underlie much of the trail
network in the Grand Canyon.
really appreciate the Grand Canyon, you have to go below
the rim and hike to its bottom, at the Colorado River, and
explore its side canyons and plateaus. A trip below the
rim provides a rare opportunity to see the geologic story
of the last 2 billion years, with each layer in the canyon
explaining successive environmental periods in Earthís
history. A book by author Colin Fletcher captures the idea
and my trip: "The Man Who Walked Through Time."
to the canyonís bottom provides more than a geology
lesson, though. The trip includes some of the most
beautiful and dramatic landscapes in the world. But I
appreciate that beauty all the more by understanding how
it came together.
Grand Canyon is quintessential canyon country. The bones
of the land here lay bare," Michael Collier writes in
"An Introduction to Grand Canyon Geology."
"Geology as cinema, moving slowly enough that we can
examine time frame by frame."
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to the bottom requires a trip of at least two days, and
staying overnight means getting a backcountry permit from
the National Park Service.
than 5 million people visit the Grand Canyon each year,
and escaping the hordes that crowd the South Rim is reason
enough to take a backcountry trip. Less than 1 percent of
the parkís visitors get a backcountry permit, and I
walked in solitude most of the trip. Permits can be
reserved four months in advance and disappear quickly if
you wait too long, due to limits designed to protect the
canyon and the backcountry experience.
took a four-day trip covering 30 miles on three trails ó
Hermit, Tonto and Bright Angel. I started on the Hermit
Trail on the parkís western edge after riding a shuttle
bus from where Iíd parked my car. I finished the trip at
the start of the Bright Angel Trail, the most popular
trail in the park, and a short distance from my car.
the Hermit Trail provides a good cross-section view of the
canyon with the Hermit Creek to the west and the Colorado
River to the north. I could make out some of the 12 layers
that, according to Collier, form the Grand Canyon. Kaibab
Limestone lined the rim, the Tapeats Sandstone was several
layers below and the Vishnu Schist formed the bottom.
layers were stacked "like a plate of pancakes, with
the newest ones going on top," said Elizabeth McKay,
a National Park Service naturalist at the park.
Vishnu Schist was formed 2 billion years ago, and water
later brought in successive layers. "Most of the rock
layers we have is just the story of sea levels rising and
falling," McKay said. The rocks and fossils in each
layer paint a picture of an environment in a particular
period: Desert covered the area during the time of the
Coconino Sandstone that can be found near the top of the
canyon, for instance.
smiled at the crushed green rock on most of the trails I
crossed. McKay told me that millions of years ago, the
seas were full of creatures called trilobites responsible
for the color of Bright Angel Shale. "Itís green
because of trilobite poop," she said.
my way through the rock layers, I was preoccupied with the
steepness of the trail. The Grand Canyon is a mile deep,
and to get from its rim to its bottom on the Hermit Trail
is a 9-mile trek. Put that way, it almost sounds like a
pleasant descent. Actually, itís quite steep, especially
the first 2.5-mile segment, which drops almost 2,000
in the Grand Canyon is similar to hiking in the mountains,
with a lot of time spent climbing and descending. Thinking
about the canyon as a mountain is also a useful geological
analogy. The canyon was shaped by the formation of the
Colorado Plateau, which was made by the same colliding of
tectonic plates that created the Rocky Mountains, and
raised this part of the country 6,000 feet, McKay said.
more than anything else, she said, the Grand Canyon was
formed through erosion by the Colorado River: "The
river is why we have this big, beautiful canyon."
river serves as a primary water source for several states,
including California. A tremendous amount of sediment adds
to the riverís destructive force, with the river
collecting mass as it winds through the arid West, growing
into a muddy beast.
followed the Hermit Trail, shortly after joining the creek
of the same name, and ended at the Colorado River. I had
planned to camp on the beach. But the roar of the Colorado
River as it slams through the Hermit Rapids convinced me I
would not get a wink. I donít know that I have ever
heard water so loud. I have slept in tents next to the
Pacific Ocean and stood next to falls in Yosemite and that
noise didnít compare to this.
set up camp alongside the Hermit Creek instead. While at
the beach, I scanned the horizons and was surprised I
could not see either rim of the Grand Canyon. I had been
swallowed by the canyon.
that day, I met a group of river runners on the beach.
Most of them work for outfitters, and when the season
ended, they got together to spend 23 days floating the
length of the Grand Canyon for fun. They told me the
Hermit Rapids were of average difficulty and the start of
progressively more serious rapids. The Hermit Rapids were
so loud I kept asking them to repeat themselves. One of
the rafters brought a surfboard and was considering a ride
on the Hermit Rapids.
the rapids are a shadow of what they were before the
damming of Glen Canyon upstream about 50 years ago. By
chance, I got to see what the Colorado River looked like
before the dam, by watching a silent movie of a river
expedition in 1923 shown at the Indian Gardens campground
on the last night of my trip. In the clip, the
free-flowing Colorado smashes boats to bits and forces
arduous portages along steep canyon walls.
other creeks flow into the Colorado, and these waterways
made the canyon up to 13 miles wide by pulling the walls
farther apart through erosion, according to Collier.
creeks helped cool me off. In the canyonís depths,
temperatures reached the lower 90s, which in the midday
sun felt much hotter. It might have been a "dry
heat," as Arizonans like to joke, but it was
staggering, regardless. I was anticipating each creek for
miles. Monument Creek provided the added pleasure of
running through a smooth rock formation. I sat in it,
blissfully enjoying the cool water as I gazed at the tall
spherical "Monument" sitting in the middle of
the side canyon. The Monument is a rock formation that
juts out of the creekís floor and rises as high as the
side canyonís walls.
cooled off, I continued hiking along the Tonto Trail,
which parallels the Colorado River and is mostly flat
except for trips into the side canyons created by the
creeks. I was walking across the Tonto Platform, a large
plateau that struck me as odd given its location deep in a
river canyon. The platform sits above the Inner Gorge, the
wall of rock leading to the Colorado River.
the time I reached Horn Creek I was burning up ó so hot,
in fact, I sat in the water even though I knew it was
radioactive from uranium mining. The Park Service says the
water is "radioactive so donít drink it unless
death by thirst is the only other option," but doesnít
say anything about sitting in it. Iíve survived at least
to write about the experience.