Fascinating courtly intrigue and bloody power games set on a generation ship full of secrets―Medusa Uploaded is an imaginative, intense mystery about family dramas and ancient technologies whose influence reverberates across the stars. Disturbing, exciting, and frankly kind of mind-blowing.” ―Annalee Newitz, author of Autonomous

Wednesday, May 30, 2012

Oak Creek Canyon, Vortex Of Fabulosity

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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