This shot from the Irish coast appears in my feed regularly, invariably captioned as 350 million years of geologic history. Actually it’s about a hundred thousand or so years of sedimentation laid down 350 million years ago, basically a snapshot of a long ago geologic moment in Deep Time. Which is pretty cool, actually, but apparently more difficult to conceptualize, though why I don’t know.
(2017)
Beautiful little piece of reddish rock, layered, I picked up along the side of the road west of the Salton Sea under the assumption it was chunk of petrified wood. Closer examination at home showed that it is more likely a fossilized and mineralized square inch of beach, or perhaps grains of sand laid down in the bed of a slow moving stream, or in an inlet of the long gone sea. Buried and compressed it hardened into sandstone and then was folded into the earth, under millions of tons or rock, and heated by the mantle below (or perhaps the energy displaced by the slow movement of the fault beneath our feet), which transformed the component sediments into something still layered but harder and more crystalline. Gneiss. Not sure where the red came from. Perhaps this was once one of the red sandstones one sees everywhere in the West, littered with dinosaur bones. There was iron everywhere once, it seems to have turned all the sediments red. Perhaps there was more oxygen in the atmosphere then, enough to turn a tree into a torch at the slam of a baseball bat, enough to oxidize all the traces of iron in the sand into a brilliant red. Perhaps. That’s the theory, anyway. Of course, most of California didn’t even exist when that famous red sandstone was laid down. California was still deep down in the mantle, or moving inexorably eastward as ocean floor before slamming into North America. No dinosaurs ever trod the sands that solidified into this stone.
Now I find this little rock here, in the sand, no metamorphic outcroppings let alone mountains for miles. So water dropped it here. Who knows how much weather that took? How many torrential rains and flash floods were required to drop this little rock here at my feet on these archaic flats? It sat there, glittering in the waning sun, surrounded by the sand verbena that clustered in vast herds across the ancient sea floor. They shivered in the dry wind, as if cold, though the temperature was near ninety and the rock was warm to the touch, as if right out of the oven. I picked it up and rolled it about in my hand, thinking of ancient worlds.
I’m still waiting for a set up for I’m sorry for your loess. It’s been years now, decades even, the funny guy equivalent of geologic time. Just my luck when I die they’ll bury me in Wisconsin and the gravedigger will complain about the crumbly rock and I’ll just lay there mute and stiff and unfunny.
(Posted to Facebook on July 6, 2019)
Yesterday’s earthquake was 7.1 near Trona and the intensity drops with the distance from the epicenter. And drops quickly. It was probably a high 6 in Ridgecrest. Had Ridgecrest experienced the full 7.1 it would have been damaged as Trona apparently is, “looking like a tornado went through the town” according to an eyewitness. Down here in LA it probably felt like a high four on the Richter scale if you lived on soil or sand, a lot less if your house is built on bedrock (we only felt the big one in our pad high atop Mt. Waverly, none of the fore or aftershocks). Quakes also feel considerably stronger if you live on the upper floors in multi-story buildings. But no one down here in LA felt anything like that 7.1 they experienced 160 miles north of us in Trona (which is still out of touch with the outside world, apparently) or 120 miles north of us in Ridgecrest.
So yes, the earthquake was stronger than the Northridge quake at the epicenter, but everyone in LA was much closer to that epicenter. Hence stuff fell down in Los Angeles in 1994, even big stuff like freeway overpasses. Probably little if anything fell down with the city limits this time.
Still, it was fun yesterday watching visiting New Yorkers freak out on social media with tales of terror and jerky videos of sloshing hotel pools. Oh the humanity.
The earthquake coverage over the weekend by CNN and MSNBC was appallingly bad. Utterly unscientific tabloid style journalism. Local coverage in LA was vastly superior. The networks could at least try to have geologists on call. Trump isn’t alone in being anti-science, apparently.
Damn, thought I found this nifty chunk of basalt out near Anza Borrego. It’s got a flat bottom (no jokes) and it is yet another rock I have on my desk for allegedly utilitarian purposes. This one, I told my wife, would make a great paperweight. But I just like rocks. I stood there in the ninety degree heat just west of the Salton Sea Basin, flowers in a zillion colors in every direction, fixated on the rock in my hand. I love basalt. I pictured it forming far below my feet, rising, cooling, a tiny bit of the earth’s mantle cooled and frozen into hard, simple stone. I was hoping it was a billion years old. I always hope basalt is a billion years old. It wasn’t. The basalt in the area was a mere hundred million years or so. Still, it does make a good paper weight, even if it’s a relative infant, mantle wise. There is something fundamental about basalt, a strength, a simple plainness, an assurance that our planet is solid and very real in the vast emptiness of the universe.
But a few minutes ago, eyes drifting from the TV where the LA Kings were being humiliated by yet another Canadian team, I started looking closely at my paper weight again. The lighter, granitic smears bothered me. Why were they there? And I hadn’t paid much attention to the bits of white on the surface. With the Kings collapsing in their own zone again, I grabbed a magnifying glass. It’s not a very good one, but through it I studied those white bits. Damn–structure. I screwed up my eyes and squeezed every bit of nearsighted vision I had remaining. Sure enough, there it was-a cylinder, ringed, tapering. Perhaps some sort of gastropod shell, some kind of pointy shelled snail maybe an inch long. I look carefully over the rock and see similar structure in some other bits. Shells. This is limestone. A very dark limestone. I took it into the kitchen and let water run over it. Wet, it’s nearly black. I found an article online about black limestone, and how to tell it from basalt. Basalt typically contains some larger non-basalt crystals. I pored over the surface of the rock again with the magnifying glass looking for crystals. Nothing. Just little hints of fossils. Bits of living things. This rock is made of organically produced structures that once contained soft bodied, skeletonless creatures, invertebrates. Organisms that needed the shelter of a shell they made themselves. Animals trying not to be eaten.
It dawned on me that I was holding in my hand the end result of the evolution of predators, of meat eaters, because before predation there was no need for shells. Everybody ate algae. There was need for shells or hard body parts or beaks or teeth. But I was holding those long deceased animals’ shells. A half billion years of protection against murder reduced to its basic minerals and a few whole bits and congealed together on the floor of the ocean after the animals shed or died in them, then pressed down by the weight of millions of years of sediments above, then hardened into rock, into this limestone. It’s like holding a handful of millions of untold histories.
The black color? I suppose it’s black the way some shales are black, shales of hardened darkened mud. I really don’t know. Basalt would have been so simple. Formed deep beneath us under the tectonic plates we stand on, and stretched out into ocean floors, then lifted up as the plates crunch into each other, pushed upward into mountains and then broken down again by water and wind and earthquakes, carried along by floods too many to count and left in the dirt at my feet between bunches of violet sand verbena and a few wild poppies. A simple story, basalt. Now I have instead a compacted chunk of the story of life, and I stare at the damn thing and feel hollow.
Oh (he says to a seismically hypersensitive friend), you work in Culver City…. That explains how you felt an earthquake (technically a microquake) that measured 2.8 on the Richter scale. I try to notice nothing below 4.0, but then I am jaded. But Culver City is built on the Los Angeles River floodplain. In fact, the Ballona Creek that trickles unnoticed though the neighborhood was an alternate channel for the L.A. river in its carefree, unchanneled days. And the soil there must be many feet deep, sediments that go who knows how far back, and are more sandy than clay, given the source (the Santa Monica Mountains). What this means for your nerves is that sandy alluvial soils are prone to liquefaction, and amplify the slightest of earthquakes, so that something beneath of dignity of an Angeleno sitting on bedrock, as in my neighborhood, is noticed by highly sensitive types in Culver City. Were it a more manly earthquake, something, say, in the vicinity of an 8 plus, the earth beneath you would be as water and you’d never be heard from again, and Amoeba could at last have what remains of your record collection.
Here’s a link to a convenient map of the Culver City liquifaction zones. They’re in teal. This map is available on Culver City’s official website, though I doubt they tell anyone, since there’s more teal than is tasteful. Teal is best in small quantities. It’s a pungent off-blue and a little goes a long way, like a rank cheese. Also it makes Culver City look so screwed. Like beyond screwed. Like doomed. Which it’s not, really. It’s that damn teal. Pastels would have been much better.
Incidentally, Culver City is the Heart of Screenland.
(Found this in the drafts, it must be a decade old at least.)
The drive to Lake Hughes via San Francisquito Canyon Road took a helluva long time but was gorgeous and great sight seeing with amazing roadcuts…man, the fault has done some terrible things to those rock layers. Some were busted into fragments and frozen in place and solidified. All this incredible, slow motion tectonic violence, immense layers of rock ground to particles, destroyed. Who knows what they were, islands, maybe, they think California is the result of islands, small little land masses all smooshed together at the edge of the North American craton. A zillion faults run through everything, Los Angeles shakes, makes us all nervous, things fall over and break. Oh well.
“Scientists Fear the BIG ONE is Coming as FOUR Major Earthquakes Strike in 48 Hours” exclaimed The Express in proper tabloid fashion. Japan is rocked by four quakes in two days, each over 6 on the Richter scale. Not a terrible quake, a 6.0 or so, but a rocker and scary enough. There were even a couple deaths. Japan handles temblors like this well. They are used to them. Of course seismologists worry that they might be foreshocks announcing a real monster of a quake, though Japan is used to those too. Alas, there is nothing unusual at all about earthquake clusters like the four The Express is screaming about, especially in Japan, where four tectonic plates–the vast North American, Eurasian, and Pacific plates, and the smaller Philippine plate–grind against each other with slow violence. The northern half of Japan is mostly part of the North American plate, the Southern half is the Eurasian plate, and the Pacific plate is forcing itself beneath the Eurasian plate (a process called subduction) at a rate of about three and a half inches a year. Sometimes the subduction process gets stuck for a few years and then, after enough pressure builds up, it moves forward with a jolt. Sometimes it’s a little jolt. Sometimes it’s a 6 point jolt. And sometimes it’s a jolt so big everything shakes to pieces and the sea comes roaring back in a tsunami. That’s Japan. We have earthquakes in California as well, of course, but no one is subducting anybody. Rather our plates are slowly grinding past one another, so that the shaking, even at its worse, cannot get to the same level as Japan is prone to. In Alaska, though, where the Pacific plate is being subducted by the North American plate, you can have earthquakes of astonishing violence, like the one that leveled Anchorage in 1964.
The Express story hinted that the quakes in Japan could set off quakes in, say, California. As if somehow earthquakes were all interconnected. And while earthquakes on the same (or on linked) fault lines can be related theoretically, ones thousands of miles away can’t possibly be, because there would not be enough energy released from an initial quake to go through thousands of miles of solid rock from Japan to California. And the fact that there are four major quakes in 48 hours in a general region–say across East Asia–is just chance, as there are hundreds of quakes 6+ every year and sometimes a few of them happen within a couple day stretch.
Remember that earthquakes, in the grand tectonic plate scheme of things, are extremely minor events, just little quivers, nothing. While to us they can be terrifying, devastating, even catastrophic, in geologic terms they are just everyday things. After all, every great mountain range in the world is the result of literally millions of earthquakes. When you think how few large earthquakes you have lived through living in, say, Los Angeles, you get an idea of the time scale in building mountains, and how we can play no role at all in that process whatsoever. Nothing alive can. Mountains rise and erode as if life never existed at all. Because in the grand scheme of things life means next to nothing, really. Life is just a process for making coal or limestone.
Brick's Science 