As
Ernie and I drove south toward Sedona on HWY 89, I mused about all of
the years I've been visiting that spot. No doubt about it –
Sedona, in its pre-vortex, pre-nouveau-riche, semi-old-west-town
incarnation was a lot more fun than it is now. But Oak Creek Canyon,
Sedona's raison d'etre, remains beautiful, magical, and delightful.
There is no place like it on Earth, and the not-so-simple reason for
that is its geology.
It's
a small canyon – at least, compared to its giant cousin up North.
Yet it shares a lot of the same layers you see exposed in the Grand Canyon. The mnemonic to remember with that chunk of the Colorado
Plateau is this one: Know The Canyon's History – Study Rocks
That're Made By Time.
Know
– Kaibab: sandy limestone, greyish-white
The
– Toroweap: also sandy limestone, a bit darker
Canyon's
– Coconino: cross-bedded sandstone
History
– Hermit: shale
Study
– Supai: it's complicated
Rocks
– Redwall: limestone (gray, but stained red by hematite)
That're
– Temple Butte: sandy dolomite, sandstone, mudstone, and limestone
Made
– Muav: limestone
By
– Bright Angel: shale
Time
– Tapeats: sandstone
All
of those layers, starting with the Tapeats at the bottom and ending
with the Kaibab on top, are Paleozoic. In Northern and Eastern
Arizona you can find at least a few Mesozoic layers too (from the Age
of Dinosaurs): Moenkopi, Moenavi, the Chinle layer of Petrified Forest National Park, the Navajo Sandstone of Monument Valley, etc.
It gets complicated, depending on how far North and East you go.
Arizona was at the edge of the continent when a lot of this stuff
formed, so you see layers from shallow seas, sandy shores, dune-y
deserts, and river floodplains.
Ernie
and I observed the whimsical shapes into which the Moenkopi layer
likes to erode when we hiked through Wupatki. If we had continued
North on HWY 89 (or the equally delightful alternate route, 89A) we
would have seen more of this layer in Utah. Heading South on 89, we
dropped in elevation, losing any hint of the dinosaur age, but
discovering some interesting layers in Oak Creek Canyon that are not
seen in the Grand Canyon. The east side of the fault that forms Oak
Creek Canyon is topped by a thick basalt layer, a lava flow. But the
Kaibab, Toroweap, and Coconino layers were eroded on this side of the
fault, so the layer under that is the Hermit.
Much
of the west side (1000 feet higher than the east) is topped with the
Kaibab limestone. The basement rock is the Redwall layer – a lot
of Sedona is built on that layer. Above that is the Supai, which is
actually a group of layers, mostly sandstone and mudstone. The
Hermit shale layer sits on top of that; despite its name, it is a
complicated mix of sandstone, mudstone, and conglomerate. And on top
of that is an 800 to 1000-foot-thick layer unique to the area: the Schnebly Hill formation, a series of gold and rust-red layers of sandstone,
mudstone, and limestone. The sandy parts were were once coastal
dunes.
Another
layer pinches out inside the Schnebly Hill formation, a greyish band
of Fort Apache Limestone. Coconino sandstone tops many of the
formations on the south side, but it merges in places with the
Schnebly Hill formation, giving the rocks a nifty striped appearance.
Like
the Grand Canyon, Oak Creek Canyon can surprise you as it suddenly
appears out of the landscape. This is particularly true if you
approach from Flagstaff. The North end of the canyon is hidden
among trees. Then you get to drive down the niftiest switchbacks on
Earth, observing some spots where the layers have literally been
pulverized by the fault. Invariably, when I'm driving through oak
Creek Canyon, I have to pull over to let impatient motorists pass.
For some reason, they like to zoom through this paradise, as if they
could actually be bored by the sight. Poor, doomed souls. I hope my
spirit will take this route to the Great Beyond, once I've left this
mortal form behind.
In
the meantime, this mortal form is very happy to hike various spots in
the canyon (after having eaten a delightful lunch at the Galaxy Diner
in Flagstaff). The first spot I wanted to hit was the trail near the
West Fork of the Creek. You have to pay to get into this spot –
it's not a State Park or a National Park. But it deserves to get a
little moolah for its upkeep, and I'm grateful it never draws the
same sort of crowd you would see at Slide Rock State Park. (Try
visiting Slide Rock in January if you just want to hike and don't
care about swimming – hardly anyone is there and it's spectacular.)
After
that, we headed for Midgely Bridge (or as the locals call it, Midgely
Bridgely). The climb down to the trail that begins under the bridge
is a little heart-stopping, but you get an amazing view of the fork
in the creek and of the Supai rocks. You can hike all the way down
to the creek from there, a hot proposition if it's summer and the sun
is shining. Fortunately for us, it was a cloudy spring day, so down
we went. Wildflowers and rock formations caught my eye on the way
down, and I saw some evidence of ancient hot spring activity in some
of the rocks that had eroded from higher spots.
Hiking
back up was much more of a challenge (for me, at least – Ernie is a
mountain goat), but we still had enough energy to explore a part of
the road (now a trail blocked to motor traffic) where the old bridge
used to be. It was mysterious, and hinted at other spots not often
accessed by casual hikers in the canyon. Some day, Ernie and I will
spend a season there, exploring the general area. This is my fond
ambition . . .
But
the day was waning, so we stopped at our favorite coffee joint on HWY
89, before looping back to do the spectacular drive along HWY 179.
Some of the niftiest formations reside there, and at one point the
setting sun set the rocks ablaze. I had to pull over to one of the
overlooks and snap some photos. I just managed to catch the sunset
lighting up the rocks before the light shifted and the moment passed.
My heart brimmed with satisfaction.
Sipping
iced mochas, we headed back to Phoenix on I-17. I would rather have
lingered and extended our day trip into days, weeks, months. But I
comfort myself by considering the fact that Oak Creek Canyon, Walnut
Canyon, Sunset Crater, Wupatki, Montezuma Castle, and dozens of other
wonderful spots are in my backyard.
I
just need to venture there from time to time.
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