Last term Caltech ran a geology enrichment field trip to the grand canyon in Arizona, which was a pretty extraordinary experience, and a wonderful opportunity to learn stuff beyond your usual specialty. For that trip I gave a talk on the mechanics of river incision, an important erosive mechanism. The previous trip was to have been to Baja California in Mexico, but at the last minute had changed due to concerns over the situation in Mexico. Statistically speaking, of course, you're much more likely to be shot in Arizona than in Baja, but at least then you'd be supporting American made weaponry. Headlines aside, Baja is actually much safer (even including Tijuana) than Los Angeles, but that's not very difficult! Headlines not aside, dozens upon dozens of executed, beheaded, and kidnapping/ransom victims hit the papers every week. Deaths in the 'war on drugs' are well in the five figures, not that far behind civilian casualties in Iraq, and over a shorter period. So it was with some trepidation that I, as usual, set aside my emotional concerns and fear and approached the issue statistically. Never-the-less, I packed light in case of robbery or misadventure!
At 6pm we met at the Arms geology loading dock. To get there, one walks through the elevated front door of the Arms building on the Rose walk at Caltech. In the entrance foyer are several large rock samples, including a large volcanic bomb. Turning to the left the curve of the staircase mimics the spirals of the diagram of the geological ages on the wall (something like:
https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj0Qbzyg0vIdLfQ0WDEEfeTVGpILuxDUFDoE-JTuEQfOvlwjM8WEPx3-sR2SMNFmV-D0um4oIIAnZ_WkUyuA0zwR8C8Q82NN0SbR3UcsqATFqGMGrxRY38WmT6_nZ1nhKo3ddYL01QBQr0/s1600/Geological_time_spiral.png) and then you are in grad student land. Several frantic-seeming icons of originality and free thought decorate the closed doors of various offices and labs. More wall poster prints of pictures from field trips in previous decades, photos of the moon, etc line the corridor as the noise of activity steadily increases. Emerging at ground level four huge white Ford Excursion (and similar) 4WDs lined the dock as last minute packing and seating allocations took place. By choice I wound up with seven undergrads in the largest of the trucks. Unlike other more technologically bold groups, roughly divided into grad students, Europeans, and S's team, we did not bring portable music players or laptops, so spent most of the trips engaged in conversation and bizarre word games, the rules of which I shall sprinkle intermittently throughout this report.
Dodging bad traffic we eventually crawled from the LA basin by the 210 East towards the 10 South and 111. By 9pm we had reached the northern shore of the Salton Sea. I put up my new bivy bag/tent combo, since I anticipated this trip would be low on trees from which to hang my hammock. Snacks and fireside chat ensued, split with a quick trip down to the seashore to shoot lasers at clouds, skim rocks, and disturb the birds which lived there. In due course it was time to retire to sleep on my luxurious customary camp mattress, made from a single car windshield reflector. I figure that a 2cm inflatable mattress is no different to a 1mm shiny thing, with similar heat properties. I took advantage of a clear view towards Jupiter to look at a few moons
Next morning we were up early, packed, munched on some breakfast, and drove around the eastern shore of the sea. With only a brief detour to be told off for trespassing on private owned railway tracks, and admiration of the bright green haze over the rather polluted sea we arrived in the Schrimpf-Davis seismic field, corresponding to the southern terminus of the San Andreas fault. Here compression gives way to rifting and several other faults. Incredibly, the Salton Sea as it exists today is anthropogenic, resulting from the flooding of the Colorado river in 1905 and filling the rift valley to a depth of 15m. 12m more and it would have overtopped to flow to the pacific ocean. Apparently it was a 'disaster' on par with the San Francisco Earthquake of 1906 and came very close to being a permanent problem. Now waters of the Colorado are used for extensive irrigation in the region and the sea is fed entirely by runoff. The field is also known for hot gas effusions giving rise to mud pots and gryphons, which are small mud volcanoes. I gave my talk on mud volcanoes (naturally). There are tens of thousands of such features around the world. The largest are found in Azerbaijan, though the man-made one in Sidoarjo, Java, Indonesia is giving it a run for its money. Down at the sea shore we found lots of dead barnacles and dried fish resulting from one of the frequent die-offs. As the salinity rises, more species of fish have found it impossible to live in. Now only the Tilapia survives, meaning that the next die-off will probably be the last. In between this quasi apocalyptic landscape of depressed and dusty towns between hyper-phosphate green fields, fumaroles, glassy obsidian beaches, and dozens of geothermal power plants I managed to cut my toe on a sharp rock. A quick application of alcohol and ethyl-cyanoacrylate (superglue) staunched the flow and permitted the persistence of sandals for the remainder of the trip. Which is lucky as I didn't bring any other shoes!
We pushed south to the border town of Calexico-Mexicali. Like most border towns, there was absolutely no reason to hang around so, navigating alternate two- and one-way streets, we drove towards Tijuana and the fault from the 2010 El Mayor-Cucapah earthquake. Modern seismological techniques have taught us that this earthquake began as a magnitude ~6.4 normal thrust earthquake, whose rupture propagated a few hundred km along the fault, in the process triggering a stronger strike-slip movement lasting for about a minute and with a total magnitude of 7.2. With surprisingly few fatalities for such a large quake, there was none-the-less impressive surface ruptures visible, one of which we were soon to discover. At the time of the quake, the road looked like this:
http://static.panoramio.com/photos/original/34083282.jpg. The road has, of course, been repaired, however on either side it's still possible to stand in cracks taller than one's head and wider than one can reach.
Turning south we drove towards the Californian gulf (part of the same rift), stopping at some rather lovely sand dunes on the way. The sun was by this stage low in the sky and sharp black hills poked through the deposited sediment in a landscape reminiscent of Mongolia. We had dinner at "Rice and Beans" in San Filipe, then drove up the coast to a marginal beach resort. I unrolled my sleeping bag on a rickety picnic table and slept under the stars. When we arrived the tidal mudflat stretched further than the eye could see. By the time we slept it had vanished beneath the incoming tide, replaced by fisherman. Another campfire raised spirits, smoked for the lasers scanning pattern, and provided a nucleus for the consumption of cheap Mexican booze.
Next morning we woke once again at 6am, packed, ate, and after a few talks on tidal flats, beach morphology, and so on, were on our way. This time we drove north, passed a routine military checkpoint and headed inland. Before long the black-top vanished and after a few turns past bewildered cows our trusty vehicles began climbing the central Baja range. At the summit we stopped to discuss the juxtaposition of differing deposits; recent volcanic tuffs and granite plutons with associated metamorphic structures overlay and interleave an ancient crustal fragment criss-crossed with eroded dykes. The road wound downwards towards Santo Tomas and Punta Cabras. By now it had begun to rain very heavily. After S stopped to help pull some stranded Mexican dudes van from the mud we shifted into 4WD and to my surprise the truck stopped sliding into the ditch. Driving through puddles that sprayed the entire car with dark orange mud comprehensively tested the sealing ability of the doors (95% solid) as well as the windscreen wipers. In due course we forded the last raging torrent and reached our campsite on an old marine terrace above a forming one. Separated by a steadily eroding cliff we managed to park the cars off the track despite being unable to see anything in the rain. Most of the evening was spent inside the car waiting for the rain to ease, though at one point a few people and I donned our raincoats and set off through ankle-deep flooding (pitch a tent? HA!) towards a distant light house and access to the beach where we hoped to find some interesting rocks. By the time we made it to the beach, everyone was pretty wet. We split the distance between the raging surf and the muddy cliff dissolving and collapsing beneath torrents of water and wandered half lost in the rainy twilight for a few minutes before turning around and walking back. By virtue of the rapidly evolving landscape, the view on the way back was quite different to the way out, and we witnessed about five landslides, each with a heart-racing 'whomp' sound. Back at the cars there was a futile effort to secure a tarp against the blustery gale before we each retired to the car. A space-blanket made an impromptu screen as the more soaked members of the party changed in the back seat. Meanwhile I shivered under a towel and came to terms with the fact that my old camera was unlikely to survive its third thorough soaking in my aged raincoat's allegedly waterproof breast pocket. At the moment there was not much to see, however. We passed around my supply of trail mix and played 'contact'. In contact, a person thinks of a word and names the first letter. Someone gives a clue for a candidate answer and if someone else realises what word that is, they say contact. The person who knows the word has a few seconds to say "it's not (whatever word is being referred to)" and if they can't, then the other two say their word simultaneously. If it's the same, the work-knower has to give out the next letter. So the game proceeds. In my day, "I spy" was pretty sophisticated!
At about 8pm the rain eased enough for S to emerge, shirtless, from his car and run around setting up the barbecue and with the help of his colleague S, excavate enough mud to start a fire. Combined with our fervent hopes for continuing rain lest crops dry out and fail, the weather cleared at about 9pm and people began to emerge from their cars, dry and smoke themselves by the fire, eat dinner and pitch tents. For a while it looked like we'd be sleeping in economy class, but in the end only four people slept in the undergrad van, including me. Dinner was infinite pasta, mushrooms and tomato sauce, prefaced with corn chips and followed with toothbrushing, an alcohol wipe bath, and a visit to the rather comfortable outhouse. It had a particularly spectacular view over the night-time ocean through the open doorway, and only leaked a little in the rain. Eventually it was time for bed, so I put on my socks to keep my muddy feet safe from my sleeping bag, unrolled said sleeping bag, and slept behind the wheel. I dreamed of driving while wearing not much more than my sleeping bag, and reflected on the awesome properties of the steering column as a clothes hook.
Next morning it was Sunday, the weather had cleared and a beautiful dawn over the ocean and nearby military radar post rubbed in just how non-functional my camera had become. The ground had dried a bit, breakfast was served (I had some of my own supplies again to avoid certain additives and milk products), I packed my sleeping bag and backpack, and prepared for our last day on the road. We walked as a group to the lighthouse and ramp, heard several talks on dinosaurs, paleomagnetism, and mechanics of wave action in marine terrace formation. We had an excellent view as part of the cliff collapsed during S's talk, somewhat distracting us! I perched on the lighthouse wall, reveling in the balance afforded to squishy sandals, and conceded the keys to P for part of the drive back. Returning along the road we came on, we were surprised to find part of it had washed out in particularly spectacular fashion. A culvert had ruptured, washing away a trench 2m wide and 4m deep. At the bottom a boat sat in the mud, possibly it had previously been used as reinforcement. While I and a few others managed to jump the chasm, the cars were not so lucky and a diversion was found around the canyons to the north. The road had dried a lot, though preserved most of the very splashy puddles that continued to leak through the doors! After a quick chat to the land owner we were on our way, pausing beneath atmospheric eucalypts in Santo Tomas for lunch. Here, like so many other places in Baja, the tourist economy is geared towards contestants in the Baja 500, an endurance 4WD race featuring cars with extraordinary power and suspensions! This sort of thing:
http://www.youtube.com/watch?v=fv0RIUl8j1w
After lunch I took over driving again and we drove north to Punta Banda near Ensenada to check out some pretty awesome rudists deposits. These extinct bivalve molluscs were the dominant reef builders before the KT mass-extinction. From here it was a straight run to the border at Tecate. We arrived at dusk and joined the queue of cars waiting to enter the US. Here we began to play another game in which a given word must be described with four or less letter words. After an hour we made it through, though the European car was delayed for a further half hour! On the other side of the border we zoomed down a narrow windy country road in the dark. The high quality of the US roads offset the inherent instability of enormous 4WDs, but somehow I managed to not kill everyone in a fiery conflagration. With one more checkpoint inside the border we shot onto the freeway and cruised as far as our stomachs would take us. Stopping at Temecula In'n'Out for dinner I made a beeline for the bathroom. Just at the moment of relief the ground swayed back and forth a few times, unnoticed but for my splayed stance before the urinal. A follow up visit to the USGS website confirmed my initial suspicion.
http://earthquake.usgs.gov/earthquakes/recenteqsus/Quakes/ci15075388.html, magnitude 3.0 is the first earthquake I've felt since moving to California more than a year ago!
I ordered the least offensive thing on the menu, swapped driving with P, and promptly fell into a food coma. Arriving back at Caltech, we fueled up our gas guzzlers for the fourth and last time, unpacked, swept, washed, signed off on the log, and left for sleep as quickly as possible.
I was in many ways surprised that there was so little drama in Mexico, given the reputation it has recently acquired for extreme violence at the hands of various drug and crime syndicates. In fact, much of the place really charmed me. There is always a soft spot in my heart for underdeveloped and economically questionable places on earth, but unlike parts of the Russian Far East, Mexico isn't frozen for eight months of the year!
