Undergraduate Field Trip 2011/Grand Canyon
By Britta Greene, A.B.2012
On March 25 at 3:45 a.m., 22 bleary-eyed geology undergrads crawled into airport vans from the geo-chemo loading dock. Twelve hours later, we boarded our new vehicle of choice: the rental minivan. With Professor Jim “speed mobile” Russell, Amanda, Jess and Caroline at the helm, we drove into the warm Arizona sun. Stopping to pick up gear, groceries and a couple of ‘in-and-out’ burgers, we headed to our first campsite in the Tonto National Forest. “Forest” refers to saguaro cacti, not trees.
The next morning, we took a hike in the Superstition Mountains, examining the volcanic tuff, gathering our first sunburns and angering a couple rattlesnakes along the way. As we were finishing up our stir-fry that night, a car drove up to the campsite. Everyone looked up as the horn blared and lights flashed. “Happy 21st!” screamed Jody’s mom and sister as they jumped out. They had flown in from San Francisco to celebrate Jody’s birthday, bringing all the necessary accessories with them — helium balloons and streamers for her tent, as well as cupcakes and sour chews for the whole crew. We wanted to have a true camp-wide celebration, but it is difficult to find firewood in a desert. Not having planned ahead, Jim balked at the $9/bushel going rate at the Tortilla Flats general store. “Let’s save those dollars for later,” he said, dreaming of tacos-to-come. A kindly RV neighbor donated some 2 x 4’s to get us going.
We then packed up our tents and headed north, to the Central Highlands. The smell of burning minivan breaks heralded us down a mountain to our first stop: Tonto Natural Bridge State Park. A ranger handed out some Travertine samples and fossils. He spoke about the largest natural bridge’s formation before pointing us to the trail. “You’ll be scrambling on some rocks soon,” he said. And he was right. The trail took us beneath and through the gaping bridge. Stumbling over the slippery limestone boulders, you could hear the telling “drip, drip” of more travertine in the works.
A stop for lunch, and we drove off again toward the travertine step-pools of Fossil Creek. The drive down to the creek was harrowing, to say the least. It was a dusty, one-lane dirt road winding steeply down the side of a mountain — no barrier between the bumping dodge caravan wheels and sudden death. We did not find fossils at fossil creek (unless you count the oxidizing iron car carcass at the base of the cliff) but we weren’t really looking. The park was beautiful, with crystal clear travertine pools ripe for swimming and sun-bathed rocks. When we arrived at camp that night, the campsite managers informed us that we in fact too big of a group to be allowed in the normal sites. Instead, we were delegated to a big lot they lovingly called “Horse Camp” — a series of nooks off a giant dirt practicing field for horses. Though the field offered a perfect spot for stargazing, it was lard bombs that provided the real entertainment of the night.
Next stop: Petrified Forest. We were now in the Colorado Plateau, a region that has been greatly uplifted without experiencing much deformation. For this reason, the region boasts amazing stratigraphic exposures. As “Painted Desert” suggest, the rocks of the region are often vividly colored —stained red, yellow and orange from oxidation. The drive to and through the “forest” was beautiful. After a slight communication meltdown between the vans’ walkie-talkie systems, we made it to the “big log” site. There, as we expected, we saw a lot of “big logs.” The forest is not a forest at all. Instead, Triassic-era tree trunks rafted by flooded streams and were buried quickly with stream sediments and volcanic ash, later to be impregnated with silica and preserved. In March 2011, the Painted Desert was definitely not the lush floodplain it once was — archosaurs running free — but it was beautiful none-the-less. We drove on to meteor crater. The meteor crater monument was one of our most offbeat stops on the trip. It was striking — a giant, eerie hole in the ground which actually demonstrates “corners” due to the nature of the impact. The crater is surrounded by a small museum and a Subway sandwich store, not to mention a gift shop larger than the crater itself. We learned its history and formation. But it was getting to be dusk, and — after five hours of driving that day — we were ready to get back to camp.
Tuesday morning we awoke bright and early, made oatmeal and instant coffee, and headed to Sunset Crater Volcano and Wupatki National Monument. The air was getting progressively colder. Sunset Crater Volcano presented a steep climb up an ashy path. Professor Russell led the way and the rest of us huffed behind. By the top we had all shed a couple pounds of warm layers. We also checked out some Sinagua cave-dwelling ruins, and learned of their response to the nearby volcanic eruption. For those people who survived, the volcanic ash actually served to revitalize local soils, allowing the Sinagua people to greatly diversify and expand their agricultural presence. We drove through Apache country, stopping at a local gas station for donuts and coffee. As we drove, we began to see canyons — like jagged scars across the flat landscape. And, finally, we reached the Grandest one.
It is difficult to summarize the geologic history of the Grand Canyon or its striking beauty. Peering over the rim, we got our first views of the canyon’s dramatic strata — from the Kaibab formation of the Cenozoic era to the Precambrian basement rocks at the base. We spent the next two days exploring the region. The second day, half of us packed down into the base, spending the night about halfway up the canyon, while the remainder of the group day hiked about halfway down on the Bright Angel Trail. The crystalline rocks comprising the “grand gloomy depths” at the base of the canyon represent two remarkable events in geologic history: the accretion of microbelts or orogenic belts into the North American craton and the later perforation of an immense volume of plutonic rock. The rocks seem to twist and ooze, remarkably different from the layered stratigraphy of the upper canyon. We dipped our toes in the freezing Colorado River and watched the sunset light up the buttes and temples above us.
And thus, back on the rim, we packed up for our trip back to Phoenix, taking our time along the way. We spent our last night at a KOA, eating famous Bluebell Ice Cream and enjoying the warm weather and beautiful stars. Bought some long-awaited tacos in Phoenix and jumped on a non-stop flight to PVD. A solid trip, to say the least.