Monday, June 29, 2015

Look West, Young Man (and Everyone Else): It's a Conjunction!

There are interesting things happening in the western skies this week. All month, there have been two bright objects in the evening sky, getting closer and closer. They aren't really getting physically closer, as Jupiter is far beyond Venus, but their line of sight is making them appear close together. Such "near-misses" are called conjunctions. They will appear closest on June 30 and July 1, so be sure to check it out!

It's been a long time since I've been able to photograph two planets in one frame at a magnification high enough to catch Jupiter's moons. Maybe tomorrow I'll even try a tripod (tonight I was just leaning on the hood of the car in the front yard).
I've been watching the dance of the planets for two weeks now. At Natural Bridges National Monument on the Summer Solstice, I caught the new moon adjacent to the planets. The Ancestral Puebloans were keen astronomers, designing their cities in the desert to align with astronomical and seasonal phenomena. Something like this in 1150 AD would most certainly have caught their attention.
It was a real privilege to be in a series of parks that are so remote from human light sources. The night skies were brilliant. The nights were nearly as interesting as the days at times. Not only is there the sky with the stars, planets, and Milky Way, but the night sounds and odors as well.

Get more information about the conjunction from EarthSky at

Sunday, June 28, 2015

Home From the Back of Beyond: Some Images of Strange and Wonderful Places

Thunderstorm near Bandelier National Monument
No, it's not a volcanic eruption, but with the light show that followed that evening, it might as well have been. We were in the high desert of New Mexico at Bandelier National Monument, and the monsoons had arrived early. The lightning flashed every second or two for hours that night. It was magical.
Joshua Trees outside of Rainbow Basin, Mojave Desert of California
I'm back from a long, but epic journey with my students through one of the most intriguing landscapes in North America, the Colorado Plateau. We crossed the California deserts to Arizona and New Mexico, swinging north through southwestern Colorado and southern Utah. Our last few days brought us through the Basin and Range Province of western Utah and Nevada.
Banshee Canyon in Hole in the Wall, Mojave National Preserve
As with all trips, I try to do new things whenever I can, but the real purpose was to open a different world to our students. This class was a hybrid course that explored the geology and archaeology of the region. It's a marvelous region for doing such a class, as humans have impacted the landscape, and the landscape has left its mark on humans.
The Citadel ruin and San Francisco Peaks from Wupatki National Monument, Arizona
The land has seen a parade of cultures over the centuries. Understanding why they abandoned the region in the past has a lot to do with understanding the limits of life there today. Sometimes the problems are the same. The Ancestral Puebloans may have left because of 25 year drought. We are in the midst of a 15 year drought today, although we experienced a very short reprieve from the dryness. A lot of ran fell in the weeks before our arrival. The desert was unusually green for this time of year.
Meteor Crater was impressive as always, a reminder that sometimes situations on our planet change in a hurry.
The Crystal Forest at Petrified Forest National Park, Arizona
Some of our stops were familiar to most people, such as Petrified Forest National Park. People may have heard of it, but many haven't visited. It's a bizarre landscape of badlands topography and horizontal forests of trees that wouldn't be out of place in the Redwood forests of California, yet are more than 200 million years old.
The slot canyon at Kasha Katuwe Tent Rocks National Monument
Other places are exceedingly obscure, although they don't deserve to be. Kasha Katuwe Tent Rocks National Monument is one of those places. Unless you are from Cappadocia, Turkey, it is one of the most unusual landscapes you'll ever see. The slot canyon is one of my favorite hikes anywhere.
The greenery was really pretty stunning after fifteen years of crippling drought. The drought is not broken by any means, but the rainy conditions over the last few weeks allowed us to imagine this landscape under a different climate regime. At Chaco Culture National Historical Park, the rangers described the plant growth as the most intense they had ever seen. The elks wandering near the campground were looking downright fat (of course the doe was probably about to drop a calf).
Chaco Canyon represented the height of the political power of the Ancestral Puebloans, in the period around 1150 AD. By the 1200s they were building the fortresses of the cliff-dwellings in Mesa Verde. It wasn't the culmination of their society, but the prelude to abandonment. Whatever the reason, the canyons fell silent around 1285. The people had migrated south and east into the Hopi mesas area and the riverlands of the Rio Grande in New Mexico.
Cliff Palace in Mesa Verde National Park, one of the largest of the cliff cities.
One of our stops was especially eerie. Castle Rock was one of the last of the Ancestral Pueblo dwellings to be constructed. It came to an end after only a decade or two with a massacre. Archaeologists discovered more than three dozen slaughtered people in the excavations.
Castle Rock, in Canyons of the Ancients National Monument
The last part of our trip went back to the geological aspects of the plateau country. Despite having visited the Natural Bridges National Monument nearly two dozen times over the years, this was the first time I was able to hike under Sipapu Bridge, probably the second largest natural bridge in the world. The opening is more than 200 feet high, and from the bottom, it is immense. Those are mature cottonwood trees in the picture below!
Sipapu Bridge in Natural Bridges National Monument
We made the very hot hike to Horseshoe Bend near Glen Canyon Dam on the Colorado River. An entrenched meander, the loop formed when the land rose, trapping a river in its floodplain pattern. The stunning cliffs are composed of the Navajo Sandstone, the remnants of a Jurassic-aged sand dune "sea" that once covered many western states.
Horseshoe Bend, near Glen Canyon Dam. The Colorado River runs clear because the dam has captured the silt that once gave the river its name. Algae is able to thrive in the clear water.
The culmination of the Navajo Sandstone is found at Zion National Park in southern Utah. The Virgin River has carved an incredibly deep slot canyon at the Narrows. In many places the river fills the entire valley floor, meaning a hike is a wet affair. I didn't hesitate!
So, I am home for a couple of days, and will try to pick up the pace with a few long-delayed blog entries. You can certainly expect more information from our last couple of trips in the plateau country as well! It's good to be home for a spell.

Wednesday, June 10, 2015

Headed into the Back of Beyond (Again)

I had hoped to finish our blog journey through the most dangerous plate boundary, but there was just too little time between real-world trips. The next journey is taking me and nearly two dozen students on a trip through time, both geological and anthropological. Our combined geology and archaeology class is exploring the fascinating landscapes of the Ancestral Pueblo people and other groups of the southwestern United States.
Archaeologists learning geology, and geologists learning archaeology. It's a symbiotic educational relationship that enriches students of both disciplines. We've done this trip a number of times, and it seems to get better every time.
This summer equinox picture of Fajada Butte at Chaco Canyon is emblematic of our trip, as we see Cretaceous sedimentary rocks of the Mesa Verde Group making up the cliffs and slopes. In the foreground, a small ruin from the people who lived on this land for more than a thousand years as a distinct culture. They then abandoned the region and 700 years later, a different group of people started to build roads again, with an asphaltic covering material (and mechanical air conditioning in their dwellings).
And all of the students are willing to dabble a bit in biology as well, especially when the object of their attention is so colorful.

Geotripper is going to be hit and miss for the next few weeks. I look forward to sharing our adventures in a few weeks!

Monday, June 8, 2015

A Geologist (also named Hayes) Sits Through "San Andreas", the Movie

What the heck is this? These are fault slickensides (scraping marks from fault motions) at Hoover Dam. Where the movie says there are no faults.

I love sitting through geology-based movies, so I can sit and smirk at the screen and criticize the horrible geology presented therein. And thus, I expected to do the same this afternoon, when I finally found time to catch "San Andreas". Mind you, there were plenty of geological issues with the movie, but I have to admit I actually enjoyed myself. It was entertaining. So here are some of the thoughts from another geologist named Hayes (the main geologist character in the movie was Lawrence Hayes. I'd feel complimented, but I noticed the movie's screenwriters, at least at some point, were also named Hayes. Plus, CalTech would never hire me).
Let's get the biggest spoiler out of the way first. Hoover Dam, Los Angeles, and San Francisco get destroyed in this movie. Strangely enough, Bakersfield gets nailed pretty badly too. The Hollywood sign and the Golden Gate Bridge get destroyed. If I was the maintenance guy for the Hollywood Sign, I'd be pretty tired of constantly replacing it by now.
Hoover Dam. It has its faults...

So, the opening scene as I recall involved a distracted young lady driving a mountain highway in the San Gabriel Mountains. A rock hits her windshield, and over the side she goes, at a rate of speed that defied the laws of gravity, and into a canyon so utterly steep that it defied gravity too. I grew up next to the San Gabriel Mountains, and yes, the mountains are steep, but yeesh. This was to establish our star as a superhero (Dwayne Johnson, aka "The Rock", doing better as a sensitive kind of guy than I would have expected).
Here's a steep canyon in the San Gabriel Mountains, but I don't think "The Rock" could fly a helicopter through it.
After the death-defying rescue, there was a lot of talking for awhile to establish the characters and bits of foreshadowing here and there. Estranged spouses, busy geologists, that kind of thing. I especially liked the poor professor very dramatically presenting the story of the worst earthquakes in history (this part was factually spot on, by the way), and then all his students waking up as the lights come back on in the classroom. One student asks ominously, "could it happen here?". What have they been studying all semester????

I get that a lot, too.
The geologists, who've worked as a team to try and predict earthquakes, predict earthquakes at Hoover Dam, and go there to investigate. Their little harmless quakes escalate quickly into a big quake, and the dam is destroyed. A couple of things: the geologists say there are no faults at Hoover Dam. The picture above is a fault at Hoover Dam. Actually, there are lots of faults at Hoover Dam. It might be more correct to say that faults there are not known to be active. Dams are known to reactivate dormant faults on occasion, due to water pressure along the fractures. Also, there was a variant of the movie trope of the black brother getting killed first. Paul Giamatti was the white guy geologist, and his associate was Asian. We immediately know he's doomed. By the way, Giamatti was pretty much my favorite character in the film. He always said very logical things, like "stop, drop and cover", and kept a cool demeanor all through the film. Oh, and laptop computers report the magnitude of earthquakes while they're still happening. It was then or later in the film that a grad student said something like "it just jumped from a 6.5 to an 8.5", again, right in the middle of the quake. It doesn't exactly happen that way. But I guess I'm being picky. Oh, and no one can predict earthquakes.
Well, almost nobody. These people predict earthquakes all the time (credit: Amanda).
The destruction of Hoover Dam showed the advances of thirty-five years of special effects technology. I liked the destruction of Hoover (or Glen Canyon) Dam in the original "Superman" movie with Christopher Reeves, but in "San Andreas" it was really something to see. I know they couldn't spend time on this kind of thing, but I sure would have liked to hear about the effects downstream on the Colorado River of having an entire year's flow happen in one day. It would have destroyed a string of dams all the way to Mexico, and flooded out of existence a number of towns. But that would have taken up an entire movie, and we had to get back to the destruction about to take place in California. Hoover was almost immediately forgotten.

An approximation of the remainder of the movie "San Andreas", courtesy of Amanda
So, for the rest of the movie, we see Los Angeles get devastated by the worst earthquake in west coast history, a 9.1 or so (no, it can't happen). Geologist realizes that it is only a precursor to a much larger quake in San Francisco, and warns people to get out of town. And go where? Modesto? We have some room in our campus gym, but that's about it. The giant quake hits, the city is largely destroyed, and our characters go about surviving one way or another. Oh yeah, there are characters in the movie. I almost forgot.

So here's the thing. The San Andreas is a transform fault, meaning it shifts sideways during earthquakes. It behaves in a segmented manner, with a history of large, but not gigantic, earthquakes  (in the real world, the quakes top out at about 7.8-8.0 magnitude, about 1/30th the size of a magnitude 9 quake. The northern segment broke in 1906, the famous San Francisco quake at magnitude 7.8 (the movie "San Francisco", 1936, still stands as one of the best earthquake movies ever). The central segment, from Cajon Pass to Parkfield, broke less famously in 1857. The southernmost segment, down in the Palm Springs/Coachella Valley region, has not gone off in about 350 years. It is pretty much the most dangerous stretch of the fault in California. No, there aren't going to be any magnitude 9+ quakes in California. You'll have to look north to the Cascadia Subduction Zone in Washington and Oregon (and far north California) for that kind of thing.

Now I know it was there because the plot progression demanded it, but this will not happen. The San Andreas will slip sideways 10 or 20 feet, but the ground isn't going to open up like this. The plot was slowing down after Ray's helicopter crash-landed in Bakersfield, and the drive to San Francisco was going to take a boring four hours. Something was needed to make them steal an airplane and get there faster. Oh, and the San Andreas fault is a right lateral fault, meaning during the quake, the side of the fault opposite the observer would shift to the right. The photo is showing a left lateral fault. Oh, and they said this was the Central Valley. The San Andreas doesn't go through the Central Valley. Oh, and because the fault motion is primarily lateral, it doesn't disturb the seafloor enough to do this:

In fact, even the world's worst earthquakes don't make tsunamis this big. Nor do they curl in like a surfer wave on the North Shore of Oahu. But heck, by now our heroes are on a boat, so there are some cool dramatic scenes of ships being destroyed. The cargo ship was great (you'll just have to see the movie). Because the plot demanded it, the movie's only "bad" guy was on the bridge when the wave hit, and he looked just like the lawyer in "Jurassic Park" before the lawyer got munched by a T-rex. Only he wasn't on a toilet.

So there are screams, and explosions, and falling buildings. Really, someone needs to sue the architects, because their skyscrapers kept falling down everywhere. This is another point that needs to be addressed. Most modern buildings will not collapse during the "big one". You will just be asking for a world of hurt if you are trying to get out of such buildings during the quake. As the geologists in the movie said, over and over, "stop, drop, and cover". You'll be much better off.
This is the absolute best lesson in the entire movie. Get under cover, preferably with an attractive person. If the building really does collapse, who do you want to spend time with while waiting to be rescued?
Those are my thoughts in the immediate aftermath of the movie, except for one thing. A really big thing, and it isn't geological. Our movie hero is a search and rescue hotshot for Los Angeles. A big earthquake hits, and his first action? He takes a helicopter that is badly needed for rescue operations, and flies off to find his estranged wife. They then take off to San Francisco in what is now clearly a stolen helicopter, in a clear case of dereliction of his sworn duty as a public servant. He crashes the helicopter in Bakersfield and steals a truck, with the justification that he stole it from someone else who had stolen it (that makes it right, right?). He gives the truck to a kindly old couple, making them guilty of receiving stolen property, and steals an airplane. He purposely crashes the plane (well, the airports were destroyed), and then steals a boat. All this to find and "rescue" a daughter who actually has spent the entire movie making incredible good and smart decisions, as well as saving a number of people (more than dad, certainly). So Ray, Dwayne, Rock, or whatever, you should have stayed in LA and saved people. Your daughter was doing fine. That's what made Giamatti, the geologist Hayes, the greatest hero: he had information that could save countless lives, found a way to pass that information on to the people of California, and thus there were still some people left at the end of the movie to rebuild the state (so it can fall over again in a century or two).

But like I said, I rather enjoyed the whole movie, and the special effects were quite good, even if these were things that wouldn't happen in real life. Don't use this movie as your education in the nature of earthquakes. I highly recommend this sort of thing: Or this:

Saturday, June 6, 2015

Driving Through the Most Dangerous Plate Boundary in the World: A Gentle Landscape Belies a Fiery Past

As we leave the Great Valley behind on our journey through the most dangerous plate boundary in the world, we finally enter the world of the Sierra Nevada. Many may think of Yosemite Valley or Lake Tahoe when the Sierras are mentioned, but the mountains rise modestly from the west side. The transition from the flat Great Valley to the gentle rolling terrain of the Sierra Nevada is not always obvious. Because most of my Sierra journeys begin there, we'll start in the central part of the range, the drainages of the Tuolumne, Merced, and Stanislaus Rivers. The picture below is the new bridge over the Tuolumne River near Old Basso Bridge upstream of Turlock Lake State Recreational Area.
This quiet gentle landscape belies a violent past in several ways. The initial rock outcrops along the rivers look sedimentary, given that they are layered and are composed of gravel, sand and silt, but the origin of some of these rocks was in fire. They are volcanic. Secondly, the lowermost rock layer found here contained gold, and miners ripped into these rocks with a ferocity that would humble today's heavy equipment operators. Thirdly, the rocks underlying these sediments record the intense deformation related to terrane collisions in an earlier time, when the Ancestral Sierra Nevada was forming.

The Sierra Nevada begins as prairie, or near the rivers, forests of cottonwood, sycamore, oak and the occasional Gray Pine. It's dry country, a far cry from the cool pine forests and alpine peaks that people usually associate with the Sierra Nevada. One can choose to follow the high-speed roads like Highway 108 out of Oakdale, or Highway 140 out of Merced, but I suggest some of the quieter avenues, like Lake Road or Highway 132. There are ranch roads that provide an even more serene journey through the foothills. The picture below is from Warnerville and Willms Roads east of Oakdale.

The basal sedimentary rock is called the Ione formation. The gravels, sands and clays of the Ione were deposited in a distinctly different environment than we see today. The sand was deposited along a beach strand, the clays (and associated low-grade coal deposits) in coastal estuaries and swamps, while the gravels settled in large rivers flowing into the coastal delta complex. Fossils in the Ione indicate tropical conditions. The Sierra of 40-50 million years ago was a coastal jungle, not unlike the coast of the Yucatan Peninsula of Mexico today!

Things changed around 25 million years ago. The climate cooled, the sea retreated to the west, and intense rhyolite eruptions began from calderas off to the east, near the present-day Sierra Crest, and farther away in central Nevada. These eruptions produced not lava, but volcanic ash, the pulverized remains of rock that exploded rather than flowed. These eruptions are the most violent known, killing all life over hundreds or thousands of square miles. The Sierra Nevada, a mountain range that had been laid low by erosion, was stirring again. The mountains were about to rise again...
Next up: mud. Lots and lots of mud...

Thursday, June 4, 2015

Short Course: Geology of the Central Sierra Nevada, June 12-14: And What a Great Setting!

Have you ever had the desire to learn about the geology of the Sierra Nevada in a spectacular mountain setting. Baker Station near Sonora Pass just north of the Yosemite National Park is the home base of the High Sierra Institute, and my colleague Noah Hughes is teaching a short field course on the geology of the Sierra Nevada on June 12-14.

The High Sierra Institute is run by the Yosemite Community College District and the class is offered by Modesto Junior College. The institute is situated along the Stanislaus River at about 8,000 feet, a short distance downstream of Kennedy Meadows. The scenery nearby is on a grand scale.
The course is worth one unit of general education credit, and the total cost is a mere $20, plus about $46 for the registration. Previous experience in an earth science or geology course is recommended, but by no means required.
Time is short, so if you are interested, please contact Noah Hughes (209-575-6173) as soon as possible. Details of the course can be found here:  It will be a marvelous experience!

I can also answer questions about the course as well.

Wednesday, June 3, 2015

Driving Through the Most Dangerous Plate Boundary in the World: The "Dr. Who" of Mountain Ranges

The Whitney Crest of the High Sierra. Mt. Whitney is just out of sight to the right.
I was torn over the title for this addition to the "Driving Through" blog series. I thought of taking the zombie approach and calling them the living dead mountains ("they keep coming at you"), or the crazed killer angle ("they're never truly dead"), but these negative for a mountain range that I love. Then it occurred to me that there is a well-loved media character who is regularly mortally wounded and is regenerated with a new body. And Doctor Who is certainly loved by millions of rabid fans. And that seemed a good analogy for the Sierra Nevada of California. The mountain range has been uplifted, deeply eroded, rejuvenated, eroded, and risen yet again, and the mountains have been different each time.
Tenaya Lake and Mount Conness in Yosemite National Park

The are at least three different mountains that occupied this part of California in the last 400 million years, and most of them were related in some way to convergence, the subduction of sea-floor lithosphere beneath the western edge of the continent. The most recent incarnation of the Sierra Nevada has an enigmatic origin, and many uncertainties remain about the specific mechanics of uplift. But rising they are, even to the present day.
Highly deformed calc-silicate metamorphic rocks in Kings Canyon near Boyden Cave.
The earliest mountains were related to the collision of exotic terranes with the western edge of North America. Some of the rocks had their origins in early Paleozoic time, and were severely deformed during the Devonian period roughly 400 million years ago. Some researchers have related the deformation to the Antler Orogeny that is best revealed in central Nevada. Had one been there at the time, the scene might have been reminiscent of some of the complicated island arcs in Indonesia.
Highly folded slate near Dial's Rock Shop near Mariposa, west of Yosemite National Park

By Triassic time, about 250 million years ago, subduction zones were directly active along the west coast of North America, and chunks and bits (the exotic terranes) became incorporated into the continent itself. Mountains were pushed up along the coast in much the same way as mountains have formed in southern Alaska, but without the glaciers. The edge of the continent was located closer to the equator than today.
Mt. Shasta, in northern California, as a stand-in for the Ancestral Sierra Nevada

By late Jurassic time, about 150 million to 85 million years ago, the so-called Ancestral Sierra Nevada mountains pierced the sky. Subduction was feeding vast batholiths of granitic rock deep in the crust, and large volcanoes and calderas caused mayhem at the surface. These mountains may very well have resembled today's Andes Mountains, and indeed, the margin at that time is referred to as the Andean-style plate margin. And then...the mountains died away again. A massive erosional unroofing began that removed 5-6 miles of overlying rocks, exposing the granitic rocks. Evidence strongly suggests that the mountains had been laid low, to mere hills (although contradictory research exists). Sedimentary rocks from 40-50 million years ago show a system of coastal marshes and estuaries, sandy beaches, and large rivers with sources in at least central Nevada, and possibly farther inland.
Much of the western Sierra Nevada is composed of gently sloping, deeply eroded metamorphic rock, covered here and there by volcanic mudflow deposists (lahars), and ash tuff.

It's only been in the last few millions or tens of millions of years that the present-day Sierra Nevada began rising to their present-day prominence. The mountains rose as a westward tilted block, outlined by major faults on the east side, and the Great Valley of California to the west. As the mountains rose, deep valleys were carved by the westward flowing rivers like the Kings, Merced and Tuolumne. In the last two million years, global cooling brought about a series of ice ages, and glaciers scoured the upper parts of the river valleys, giving rise to the spectacular gorges that we visit today, Yosemite Valley being the epic example.
Yosemite Valley from the vicinity of Turtleback Dome.

So, our drive through the most dangerous plate boundary in the world will continue, following pathways into the heart of this mountain range that is both ancient and youthful at the same time.