Home From the Back of Beyond: Some Images of Strange and Wonderful Places

Thunderstorm near Bandelier National Monument

No, it's not a volcanic eruption, but with the light show that followed that evening, it might as well have been. We were in the high desert of New Mexico at Bandelier National Monument, and the monsoons had arrived early. The lightning flashed every second or two for hours that night. It was magical.

Joshua Trees outside of Rainbow Basin, Mojave Desert of California

I'm back from a long, but epic journey with my students through one of the most intriguing landscapes in North America, the Colorado Plateau. We crossed the California deserts to Arizona and New Mexico, swinging north through southwestern Colorado and southern Utah. Our last few days brought us through the Basin and Range Province of western Utah and Nevada.

Banshee Canyon in Hole in the Wall, Mojave National Preserve

As with all trips, I try to do new things whenever I can, but the real purpose was to open a different world to our students. This class was a hybrid course that explored the geology and archaeology of the region. It's a marvelous region for doing such a class, as humans have impacted the landscape, and the landscape has left its mark on humans.

The Citadel ruin and San Francisco Peaks from Wupatki National Monument, Arizona

The land has seen a parade of cultures over the centuries. Understanding why they abandoned the region in the past has a lot to do with understanding the limits of life there today. Sometimes the problems are the same. The Ancestral Puebloans may have left because of 25 year drought. We are in the midst of a 15 year drought today, although we experienced a very short reprieve from the dryness. A lot of ran fell in the weeks before our arrival. The desert was unusually green for this time of year.

Meteor Crater was impressive as always, a reminder that sometimes situations on our planet change in a hurry.

The Crystal Forest at Petrified Forest National Park, Arizona

Some of our stops were familiar to most people, such as Petrified Forest National Park. People may have heard of it, but many haven't visited. It's a bizarre landscape of badlands topography and horizontal forests of trees that wouldn't be out of place in the Redwood forests of California, yet are more than 200 million years old.

The slot canyon at Kasha Katuwe Tent Rocks National Monument

Other places are exceedingly obscure, although they don't deserve to be. Kasha Katuwe Tent Rocks National Monument is one of those places. Unless you are from Cappadocia, Turkey, it is one of the most unusual landscapes you'll ever see. The slot canyon is one of my favorite hikes anywhere.

The greenery was really pretty stunning after fifteen years of crippling drought. The drought is not broken by any means, but the rainy conditions over the last few weeks allowed us to imagine this landscape under a different climate regime. At Chaco Culture National Historical Park, the rangers described the plant growth as the most intense they had ever seen. The elks wandering near the campground were looking downright fat (of course the doe was probably about to drop a calf).

Chaco Canyon represented the height of the political power of the Ancestral Puebloans, in the period around 1150 AD. By the 1200s they were building the fortresses of the cliff-dwellings in Mesa Verde. It wasn't the culmination of their society, but the prelude to abandonment. Whatever the reason, the canyons fell silent around 1285. The people had migrated south and east into the Hopi mesas area and the riverlands of the Rio Grande in New Mexico.

Cliff Palace in Mesa Verde National Park, one of the largest of the cliff cities.

One of our stops was especially eerie. Castle Rock was one of the last of the Ancestral Pueblo dwellings to be constructed. It came to an end after only a decade or two with a massacre. Archaeologists discovered more than three dozen slaughtered people in the excavations.

Castle Rock, in Canyons of the Ancients National Monument

The last part of our trip went back to the geological aspects of the plateau country. Despite having visited the Natural Bridges National Monument nearly two dozen times over the years, this was the first time I was able to hike under Sipapu Bridge, probably the second largest natural bridge in the world. The opening is more than 200 feet high, and from the bottom, it is immense. Those are mature cottonwood trees in the picture below!

Sipapu Bridge in Natural Bridges National Monument

We made the very hot hike to Horseshoe Bend near Glen Canyon Dam on the Colorado River. An entrenched meander, the loop formed when the land rose, trapping a river in its floodplain pattern. The stunning cliffs are composed of the Navajo Sandstone, the remnants of a Jurassic-aged sand dune "sea" that once covered many western states.

Horseshoe Bend, near Glen Canyon Dam. The Colorado River runs clear because the dam has captured the silt that once gave the river its name. Algae is able to thrive in the clear water.

The culmination of the Navajo Sandstone is found at Zion National Park in southern Utah. The Virgin River has carved an incredibly deep slot canyon at the Narrows. In many places the river fills the entire valley floor, meaning a hike is a wet affair. I didn't hesitate!

So, I am home for a couple of days, and will try to pick up the pace with a few long-delayed blog entries. You can certainly expect more information from our last couple of trips in the plateau country as well! It's good to be home for a spell.

Vagabonding across the 39th Parallel: Who knew the hoodoo was in Castle Rock?

When you set out with no plan (or at least no detailed one), you just never know what is going to happen next, and what interesting places you can discover. We were vagabonding our way across the 39th parallel, and had reached the Wasatch Front in Utah. After looking at a great collection of artifacts and petroglyphs at Fremont Indian State Park, we were looking for a place to camp for the night. Signs at Fremont pointed down a dirt road to a campground. We checked it out, and what a surprise!

Castle Rock Campground is in a little hidden valley away from the noise of the interstate, and what a setting! The camp is surrounded by an intricate maze of hoodoos and high rhyolite cliffs. How did this landscape come about? And what is a hoodoo?

Hoodoos come about when relatively soft sediments include large boulders or capstone layers that can protect the underlying rock from being washed away. The effect produces towers and spires and a maze of winding narrow washes.

It is an otherworldly effect...kids would love this place, but keep a close eye on them! It's a lot easier to climb up these rocks than to climb down.

The photography opportunities are unending...the evening light was brilliant. Castle Rock is a spectacular place to camp. The camp itself is shaded by cottonwoods, and is nicely designed with well-spaced campsites. It was practically empty when we arrived (on a Friday!), but a number of people eventually showed up.

Once we climbed to a vantage point over the valley containing the campsites, we started to get curious about the rocks themselves. They weren't much like the ones exposed at the museum only a mile away, and the rhyolite cliffs were hundreds of feet high, unlike the cliffs down lower, which were only a few tens of feet high.

The hoodoos are composed of conglomerate, sandstone, and siltstone, the kinds of sediment associated with deposition by rivers and streams in alluvial fans and shallow lakes. The coarseness of the sediments suggests a local source area. A few light-colored ash layers in the sediments provide the opportunity to date the sediments.

In the last post, we discussed the eruption of the Joe Lott tuff, which took place 19 or so million years ago. Soon after the blasts, volcanism declined, and the region began to stretch. The onset of basin and range extension caused numerous fault valleys to develop, and these local basins started filling with sediments washed from the adjacent uplifted mountains. The layers at Castle Rock were laid down between about 14 to 5 million years ago, on top of the tuff deposits.

At the upper end of the camp, something else had happened. The layers weren't horizontal anymore, they were dipping steeply to the north, right next to the high cliffs of rhyolite. I wanted to investigate the contact to see what was going on.

But the sun was dropping below the horizon, so we would have to wait until the next day.

We went to bed under a full moon.

The next morning we scrambled up some rough topography to try and get a view of the contact zone.

It turns out that the contact is a fault zone, and that the tilted layers represent a drag fold caused by the downward movement of the valley block. The fault is a normal fault (the headwall has dropped relative to the footwall), the kind caused by extensional forces, which is what would be expected here.

The rhyolite was just as thin as it was in other parts of the state park, but because it had been tilted, it appeared to be much thicker. The deformation caused cracks and fractures in the rhyolite that developed into strange erosional forms like the hollows, arches, and caves of tafoni weathering.

It was great place to explore! After a few hours we packed and hit the road, heading east on Interstate 70, wondering what would come next. The answer wasn't long in coming, but that's another post!

For more information on the geology at Castle Rock Campground, check out:
http://geology.utah.gov/surveynotes/geosights/castlerock.htm
and chapter 12 of Geology Underfoot in Southern Utah, by Orndorff, Wieder, and Futey