To put it mildly, IT WAS AWESOME!!!!!
Leaving the white and green hills of Vermont just in advance of the onset of mud season, to spend a week in sunny southern California, met all the hopes of the party of 14 from the Department. The group spanned from senior to junior faculty, from freshman to senior students, and also included the most welcome addition of a spouse.
San Diego was the jumping off point with a late arrival and a quick set-up for camp. Rising early with everyone still being on Vermont time, the group headed east across the Peninsular Ranges of the Southern California Batholith. Coarse igneous rocks were deeply weathered and produced spectacular spheroidal weathering. Poikilitic biotites the size of quarters made mirror reflections in all directions during lunch, and strong ductile shear features topped off the drive.
We arrived in Anza Borrego Desert State Park for a late afternoon hike through more intensely sheared grantites and associated older host rocks, until we came upon strongly flowing water, always a treat in the desert, that led upstream to a palm grove. It was impossible not to wonder what the earliest human inhabitants would have thought about why the water springs forth so strongly and then dies just below the grove.
Morning departure came early after what had become our staple bagels, cream cheese and jelly (with lots of strange alterations and additions), topped off with cowboy coffee. Our hike that morning was into a deep canyon cut into thick, heavy conglomerates, and we struggled to keep moving due to the overwhelming number of things to look at. Ultimately we reached a major fault zone that brought intensely folded older sandstones up onto the gravels, with more questions asked than answers provided.
Algodones Dunes was the next destination, down near the southeastern corner of California, not far from Mexico. Kevin Chin’s high speed roll down the 100-foot face of a dune was certainly a highlight, combined with Charles Poe’s self-filmed roll replete with “terrorist” head cover to avoid sand in the orifices (films to come shortly).
Night three was on the sweet-smelling (ha-ha) eastern shore of the Salton Sea in a primitive campsite. We wandered out to the water’s edge in the morning, crunching through salt-crusted gas volcanoes driven by bacterial decay just below the surface. Not your typical Vermont scene, with thousands of fish carcasses strewn about. The famous date shakes of the region were our next stop, and we lay around on the grass afterward trying to recuperate from the calorie overload. We gamely headed north and spent the rest of our day in Painted Canyon in the Mecca Hills, first walking the surface of a major unconformity with more than a billion years of rock record missing, and then we began our ascent into a narrow slot canyon. “This is the most awesome thing ever!” was heard more than once as we climbed slopes and ladders, eventually emerging at the top of a ridge with more canyons that you could count laid out before us. A late lunch of sandwiches, fruit, gorp and water got us fueled up for the descent, and we headed down to begin our trek up across the San Andreas Fault to get to Joshua Tree National Park for the night.
Another excellent meal, always with a Tex-Mex underlying theme including lots of fresh vegetables and several varieties of hot sauce to choose from, led to our fourth night under the stars, this time pretty far removed from any artificial light. We hung around camp to examine the outcrops, pinning down the contact between Mesozoic granitoids and their Precambrian migmatitic host rocks. If you didn’t know better, you could almost see the host rocks sweating out granite to form the plutons. We toured the park on the geology loop, seeing ancient eroded landscapes and the shallow roots of young volcanics, and then we scrambled up into the rounded and sculpted granites to examine shear zones, aplite-pegmatite systems, and intense weathering features. After a trip to the overview near the south edge of the park, with the San Andreas laid out at our feet a couple thousand feet below, we drove out to the northwest and over to Silver Lake State Park for the night, north of San Bernadino.
“Up and at em'” was the daily process and early the next day we were on our way to hike across alluvial fans of the Cucamongo district, specifically up into Day Canyon in the Etiwanda Preserve. It was like having boxes of rounded and polished introductory geology rock samples delivered to your feet, making walking difficult because it’s hard to walk, pick up samples, look through your hand lens, and discuss what you see all at the same time! Fault scarps from recent, south-directed thrusts of Precambrian basement onto the fan gravels were well displayed, and the evidence for a continuous history of flash flooding and fan development was about as stark as you could ask for. Local residents have struggled for more than a century with the raging waters, and current efforts include a 5- to 10-acre empoundment structure that requires regular maintenance.
With our time drawing to a close, it was time to head south. We worked our way back up into the high ground of the Peninsular Ranges for another review of pluton development and emplacement, complete with xenoliths cross-cut by multiple stages of felsic dikes. Once again we found sieve-like “gigantic” poikilocrysts, this time of hornblende in noritic gabbros. The effort included one climb to see vesicular basaltic andesites structurally above the plutons. Night found us nearby, still at high elevation above Lake Elsinore, camped in a primitive group site where we saw no one else until we hit the road in the morning.
Beach work was the order of the day to close out our week, starting by descending the high eroded cliffs down to the San Onofre beach just south of the SONGS reactor. Landslide deposits confused us, flat-lying sedimentary rocks were ideal to display off-set of recent thrust faults, old wave cut benches were laid out for us to walk on, and the exposures were capped off with a repeating story of recent reverse faults bringing complexly deformed bedrock up onto formerly overlying gravels and conglomerates. From there we dashed to the Cabrillo National Monument at Point Loma for a final view of California coastal geology. Tracks, trails and burrows were displayed better than you could find in a museum, and old unconformities with giant lag boulders at the contact mirrored the current condition at the shore where the surf crashed across a modern bench with its own exotic boulders rolling across the eroding surface.
Our traditional restaurant dinner was a fitting way to close the week, with superb Italian cuisine from Osso Bucco to spaghetti with meatballs. Travel was simple for departure on the red eye out of San Diego, but got a bit delayed for the link from D.C. up to Vermont. Nonetheless, we all arrived safe and sound, excited to jump back into the remainder of the Spring semester and already planning next year’s adventure.