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number nine
Unkar Delta
River Mile 72

Overlooking the Ruins

We’re hiking along a ridgeline toward the Unkar Delta overlook, where this group of UC Davis graduate students has been promised stunning views of archaeological ruins and the Colorado River’s Unkar Rapid.

Just a few feet in and already the view is not too shabby. One of the ecogeomorphology class’ instructors, Sarah Yarnell, points out the sandbars, widening canyon and river below. She launches into a talk about the fan-eddy complex, which is one of the most influential natural forces of the Colorado River.

When debris — like sediment, cobbles and boulders — flows down a tributary and spills into the main channel it creates a debris fan, not to mention some thrilling rapids and vertical drops.

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Fan-eddy complex, simplified

The fan-eddy complex is a sequence that helps give the Colorado River its “river profile” of calm pools of water upstream piled behind a rapid, which gives way to a complex flow zone downstream with side eddies and gravel bars. That combination helps create ecological niches in the canyon for native fish and other species.

Now that Glen Canyon Dam prevents most sediment from naturally moving down the main stem, the Colorado River’s hundreds of tributaries are largely responsible for moving sediment and big boulders into the river.

“The fan-eddy complex creates sandbars and a network of pockets where fish and bugs can hang out,” Sarah says. “These debris fans are creating their habitat. The river may be too cold for some species, but the sandbar is like a fish nursery there.”

Unkar Delta overlook

We arrive at the Unkar Delta overlook and it is, as advertised, stunning. We stand on red cliffs rising dramatically over the river, which wraps around the delta in a hairpin curve.

A woman looks out over the river from high on a ridge abover the Unkar Delta
Erin Sattherwaite, a marine ecology graduate student, takes in the view of the Unkar Delta overlook. Photo: Joe Proudman/UC Davis

The Unkar Delta was formed by rock debris carried from the Grand Canyon’s North Rim by Unkar Creek. The plain stretches out broadly, and we spot rectangular outlines of rocks, the remnants of dwellings used by ancestral Puebloans. They lived and farmed in the area from about A.D. 850 to 1200, planting corn, squash and beans on irrigated fields and terraces near the river and creek.

The students are introspective, finding ledges and nooks where they can sit, stare and absorb. There’s the beauty in front of us, the remnants of human and natural history below and around us, and there’s Unkar Rapid, burbling just around the curve. It’s one of a handful of rapids we have left on this trip and a reminder that our time will soon draw to a close.

Graduate student Michael Kenney points out the Great Unconformity. - Credit: Mille Levin / UC Davis

The students learn about the fan-eddy complex, one of the most influential natural forces of the Colorado River. Photo: Joe Proudman/UC Davis

Water disasters and other scary stories

Most nights after dinner, we sit on the beach, telling and listening to stories. Tonight’s theme seems to be water disasters.

The guides from UC Davis Campus Recreation’s Outdoor Adventures have been down this and many other rivers before. Some have run rivers for more than two decades. Tonight they talk among themselves about flips, crashes and other disasters, be it in the ocean or river. They tell of storms and capsizes. Of “holes” sucking them into rapids.

There’s a lot of laughter — you can do that when all ends well. But I sense that they’re mentally preparing themselves. Tomorrow, we’re going to see some pretty big rapids. The biggest ones of our trip. I admit, I’m a little bit scared, but it’s going to be OK.

- Kat Kerlin

grey arrow Continue the journey at Stop 10, 85 Mile Rapid

“I’m writing this by moonlight, the sound of river running below camp. I’m leaning against a large rock in the sand. Overhearing the students playing a game by the camp circle. Here, in this incredible place and out of my element, I feel connected more deeply without all the typical distractions. It’s sad to think we have only two more days on this river—more than most people get in a lifetime — before it’s time to hike up Bright Angel Trail to the rim and civilization. But tonight, it’s me and the stars and the rushing river.”
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Next Stop...85 Mile Rapid