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News and views from the geologic realm



Last Build Date: Tue, 24 Apr 2018 18:23:09 +0000

 



If These Cliffs Could Talk: Tis-sa-ack and Tu-tok-a-nu-la (A Geologic Love Story Redux)

Tue, 24 Apr 2018 18:23:00 +0000

I've been to Yosemite Valley twice in the last month, including a day when the Merced River was still at flood stage. I was reflecting on the many journeys I've made there with my students and with Mrs. Geotripper, and what a stunning place it truly is. I was thinking of a new angle to present some pictures of the latest trips, but then my good friend @phaneritic on Twitter asked a question about quotes concerning the valley that don't involve the writings of John Muir (as wonderful and poetic as his words were). I realized I had written about some of the legends of Yosemite a few years ago, and decided it was time to bring some of them back, in case they were missed before.These stories also have relevance to the moment because of the decidedly stupid legal war over trademarks being waged between the National Park Service and the recently departed Delaware North concessionaire. One current sign of the ongoing legal battle is the new name for the Ahwahnee Hotel ("Majestic Yosemite") and Curry Village ("Half Dome Village"). Half Dome is a very plain name for such a stupendous rock, and I am thinking the park service missed an opportunity. Tis-sa-ack Village might have been a mouthful to pronounce, but it gives the rock a history and an air of mystery.And so here it is, the story of Tis-sa-ack and Tu-tok-a-nu-la, a geologic love story, first published in November 14, 2014:Tis-sa-ack (Half Dome) from near Yosemite FallsA love story...Unnumbered snows have come and gone since The Great Spirit led a band of his favorite children into the mountains, and bade them rest in this beautiful Valley of Ah-wah-nee. They were weary and footsore, and were glad to rest after their long journey. Here they found food in abundance. The streams held swarms of fish, meadows were knee-deep in sweet clover, great herds of deer roamed the forests in the Valley, and on the high mountains, oak trees were bending under the weight of their acorns, grass seeds and wild fruits and berries grew in bountiful profusion. Here they stayed and built their villages. They were happy, and multiplied, and prospered and became a great nation.North Dome, Washington Column, and Half Dome in the cloudsHow many stories begin in paradise?I find the myths of different cultures to be fascinating. They provided their people with an explanation of the unexplainable, a comforting story that suggests there is order in the apparent chaos of the universe. In the perspective of geology, we can sometimes see the whispers of eyewitnesses to significant geologic events: the eruption of Mt. Mazama, for instance, which resulted in the formation of Crater Lake, is described in Native American oral histories. In this post we see one of the legends of Yosemite Valley, with all the embellishments and cultural biases of a 1922 narrative. Still, it's a good storyTo their chief came a little son to gladden his heart. They wanted this son to become a great chief, capable of the leadership of a great people. He was made to sleep in the robes of the skins of the beaver and the coyote, that he might grow wise in building and keen of scent. As he grew older he was fed the meat of the fish, that he might become a strong swimmer, and the flesh of the deer, that he might be light and swift of foot. He was made to eat the eggs of the great crane, that he might be keen of sight. He was wrapped in the skin of the monarch of the forest, the grizzly bear, that he might grow up fearless and strong in combat. So many stories come with the hero, and the most interesting stories have heroes with flaws...they had everything. But then things happen. The world and the people who live in it are not perfect. And frankly, life would not be interesting.And, when he grew to manhood, he was a great chief and beloved of all the people. His people prepared for him a lofty throne on the crown of the great rock which guards The Gateway of the Valley, and he was called Tu-tok-a-nu-la, after the great cranes that lived in the meadow near the top. The people of Ah-wah-nee were happy, for Tu-tok-[...]



Do You Know the Tallest Waterfall in Yosemite Valley? You Might Be Wrong!

Sat, 21 Apr 2018 18:38:00 +0000

Quick quiz: What is the name of this waterfall?What is the highest waterfall in Yosemite Valley? Depending on the parameters one can use to determine "height", your assumption may be wrong! Most "authorities" recognize Yosemite Falls (2,425 feet/739 meters) as the highest in Yosemite Valley and North America, and somewhere around the fifth or seventh highest in the world. But it depends how you decide to measure waterfalls. By a different metric, Yosemite Falls aren't even the highest waterfalls in Yosemite Valley. It's the word "waterfalls", in the plural, that makes the difference.There is no doubt that Yosemite Falls is one of the most stunning sights on the planet. A chance movement of a glacier 13,000 years ago forced a middling stream from its old channel to the left of the current waterfall, forcing Yosemite Creek to drop right off the edge of the sheer cliff. You can see the old channel almost hidden in the shadows in the photo above.The fall makes a sheer plunge of 1,430 feet (440 meters) at the Upper Fall and then cascades through a series of steep ledges called the Middle Cascades for 675 feet (206 meters). There is a final drop of 320 feet (98 meters) at Lower Yosemite Fall. The Middle Cascades are generally hidden from view unless you hike the steep trail up to the top of the falls (below).Part of the Middle Cascades (April 2003)But if one decides to be a purist about such things, one can define a waterfall's height on the basis of the greatest freefall. By that metric, Yosemite Falls still is an imposing 1,425 feet (739 meters) high. But it also means it's not even the tallest waterfall in Yosemite Valley.Many first-time visitors to the valley are drawn to Bridalveil Falls (620 feet/189 meters) because it is the first major waterfall visible as one enters the valley. But when standing at the base of Bridalveil, they see another high waterfall across the valley and wonder if it is Yosemite Falls. It's not. It's called Ribbon Fall, and it has a single drop of 1,612 feet (491 meters). That's nearly 200 feet higher than Upper Yosemite Falls (it's the one in the picture at the top of the post). It is less familiar than many of the other waterfalls because it is usually dry by June when the majority of people visit the park. But if you get the privilege of seeing by visiting in the spring, you are in for a treat.I have been trying to get a particular picture of Ribbon Fall for a long time. When driving towards the Tunnel View parking lot from Bridalveil Falls, there is a panorama of Ribbon Falls and the cliff of El Capitan, but there is no way to stop or pull out to get the shot, and the road is too narrow for walking. But yesterday I was there with my students in a bus. Since I wasn't driving, I was ready with the camera as we came back down the road, and I finally got it (below).Ribbon Falls is one of many treasures that make a spring visit to Yosemite Valley a worthwhile effort.[...]



My Favorite Moment of the Semester, and No, It's Not the End of Finals

Fri, 20 Apr 2018 03:33:00 +0000

It's possible that I have the best job in the world. I know there are people who make more money and all that, but making money can only provide so much satisfaction. I get to be involved with people working hard to make their lives better, and I have to say that there is almost no feeling better than witnessing the success of people who mastered difficult concepts under your guidance. Graduation ceremonies are fun in their way, but my favorite moment comes just before finals week and all the ceremonies that follow. It is our Science, Math and Engineering Awards. It's the moment when we can honor and congratulate those students who rose above whatever challenges they had and excelled in their science courses here at Modesto Junior College.

And that's one thing about being in a small department with relatively small classes. You learn in great detail the kinds of things that students in today's community colleges are up against. There are job pressures (in many instances they work at more than one of them). Many of them have young children with all of the attendant challenges of parenthood on top of their school work. Many come from families with serious problems, and many are the first in their family to take on the responsibility of a college education. For them, it's a victory just to be in college at all. Imagine the pride they have when they overcome these serious challenges and succeed.

And that's what today is all about. I got to honor my outstanding students with Certificates of Achievement in Geology (there were five of them, in the picture above; the others were honorees in the Earth Sciences). I also got to surprise Marissa, third from the left, with the Outstanding Student in Geology for the academic year.

Oh, I was also privileged to be the speaker for the night's festivities. I was having a bit too much too much fun criticizing the depiction of geologists in Hollywood movies. You can get a hint of the nature of my remarks here: https://geotripper.blogspot.com/2008/03/accretionary-wedge-carnival-7-hollywood.html.



After the Deluge: Dam! We Almost Lost a Dam!

Sat, 14 Apr 2018 23:41:00 +0000

But for the vagaries of the weather, we would never have seen it. Running field studies courses in the winter and spring always involves an element of chance, but in the dry year that we've had, it seemed safe enough to schedule a trip to Yosemite National Park in early April. But as the previous two posts have shown, an epic atmospheric river storm, a Pineapple Express, pummeled the area last Saturday. We postponed our trip to Sunday, and had a fine day, but we reversed the direction of our trip, because we still weren't sure if Yosemite Valley would open up in time for us to visit. If the valley remained closed, we wanted the choice of going to Hetch Hetchy Valley instead, and to allow that we needed to go by way of Highway 120 through Big Oak Flat and Groveland, instead of Highway 140 through Mariposa.I had heard that Moccasin Reservoir almost failed a few weeks earlier, but didn't give it much thought while I was bustling about trying to think of alternate field trip stops. We had left the Red Hills Area of Critical Environmental Concern and were approaching the Priest Grade when I remembered the dam episode. During an intense storm on March 22, floodwaters overwhelmed the spillway of the small earthen dam on Moccasin Creek. Moccasin Dam is about 700 feet across and about 60 feet high, holding back about 554 acre-feet of water when full. There is one very strange fact about the dam. Even though it blocks Moccasin Creek, it doesn't hold water from Moccasin Creek! In instead contains Tuolumne River water that has been diverted into the Hetch Hetchy system and pumped through a hydroelectric plant on lower Moccasin Creek. The dam is a small forebay that feeds into the much larger Don Pedro Reservoir and Lake just a mile downstream. Moccasin Creek was heavily mined during the Gold Rush, and the sediments may be contaminated by mercury and other toxic metals related to the gold extraction process. The water of Moccasin Creek is diverted around the reservoir.As we drove by, I commented on the radios that the flood had happened, but I saw that a lot of the damage was visible from the highway and we screeched to a stop to have a look. It had clearly been a serious storm. The flood had ripped out trees, roads, and telephone poles. The dam itself looked undamaged, but the spillway downstream had been severely eroded. Few people were threatened by the flooding, but roads were closed. If the dam had failed, the effects would have been limited because Don Pedro Lake, only a mile downstream, would have easily absorbed the extra water.Maybe the saddest aspect of the flood was the near destruction of the fish hatchery. As can be seen in the picture below by Mark Brooks and aired on several news outlets, the entire hatchery was flooded, and all of the fish either killed by turbulent mud, or carried downstream to Don Pedro (when does fishing season start?).Geology and weather are capricious beasts. One of the lessons of the earth sciences is that no place anywhere on this planet is free of the possibility of natural disasters. Some places are more dangerous than others, but there is always a big advantage to understanding the possible hazards where one lives and works. One may think they may never happen in one's lifetime, and they might not, but that's a dangerous gamble to make.Photo by Mark Brooks[...]



After the Deluge: Yosemite Valley a Day Later (and a sight I've never seen in more than 100 visits)

Fri, 13 Apr 2018 04:13:00 +0000

Yosemite National Park is a treasure. And the gem of the park is Yosemite Valley. There are spectacular spots to visit throughout the park and region, but ultimately, the sheer granite walls and booming waterfalls are the heart of this part of the Sierra Nevada. Most people know this of course, and the valley struggles with the desires of millions of people who wish to see the park for themselves. There are horror stories of absolute gridlock throughout the valley, with upset families who wait for hours just to get into the park, and then never find a place to park and get to know it better. I can barely imagine the frustration of devoting a hard-earned vacation to see the place and then have it spoiled by the chaos of too many people.Bridalveil Fall (620 feet) and the Leaning Tower at the west end of the valleyI've been privileged to live relatively close to the park, and in 30 years, I've been there over a hundred times. I've quite literally never had a bad time, but part of the reason is that I've been able to pick and choose the times I visited. It turns out that the time most people set aside for vacation, in July or August, is possibly the least interesting time to do so. It's still spectacular, but the crowds are the worst, the waterfalls mostly dry, and it's hot. In fall, the valley is quieter, and the oaks and dogwoods add a splash of color. Winter brings snow and silence. Spring is noisy because of the waterfalls booming from the canyon rim. If your schedule allows, go there in the off season!Ribbon Falls only flows in the spring; it's the highest free-falling waterfall in the park at 1,612 feet.Of course, if you come at another time of year, you would be taking a chance with the weather. That's what happened to me last week. I was scheduled to take my students there on Saturday, but fate intervened with an epic warm tropical storm that dumped inches of rain on the snowpack. The Merced River swelled to nearly 14 feet (10 is official flood level) and major roads in the valley were under a few feet of water. For one of very few times in its history, the park was closed as a precaution and people were evacuated. I was luckily able to reschedule for Sunday, because the sun came up in a cloudless sky and the difference between the two days was astounding.Upper Yosemite Falls, 1,430 feet high, the second highest in the park after Ribbon Falls (above).I included some direct comparisons between Saturday and Sunday in my previous post (with thanks to the Park Service for posting pictures of the storm). Today I am offering views of some of the classic views in the park, revealing the vast amounts of water still flowing into and through the valley. The Merced River had subsided somewhat but was still flowing at flood level, but only barely. The main effect was the low-lying valley meadows that were still underwater (the next two pictures).A flooded Cook's Meadow forms the foreground for Upper Yosemite Falls.The occasional flooding of the meadows is part of what maintains the meadows as open areas. Tree saplings are smothered underwater, and only grasses and sedges that can survive the high water table. Not all of the meadows have survived however. Since the park was established, some of the original meadows have progressed into thick forest...there are only about 65 acres of meadows left out of the original 745 acres that existed at the time of European discovery. The growth of the forest is largely the result of fire suppression. The park service will occasional burn some of the meadow margins on purpose to help maintain the integrity of the open spaces.No visit to Yosemite Valley would seem complete without a view of Half Dome, but I have been there a fair number of times when my students never had a chance to see it. When rain is falling, it can be completely hidden in the clouds. But on Sunday it was there in all its glory. The unique shape is due to a combination of exfoliation (the fracturing of rocks parall[...]



The Difference a Day Makes: Yosemite 24 hours after the Deluge

Mon, 09 Apr 2018 07:23:00 +0000

Photographed by Garry HayesFirst off, thank you to the National Park Service for making the flood photographs available on their Facebook page. And second of all, kudos to the National Park Service for weathering the flood and opening the park again so soon afterwards.I was in Yosemite Valley today, leading my students on a postponed field studies class in the park. Why did we postpone the trip? Well, mainly it supposed to take place on Saturday, but it turned out that the valley was in the midst of dealing with one of the larger floods it has experienced, about the fourth or fifth largest in 30 years or so. Plus, they closed and evacuated the park in advance of the storm. They only opened up again at noon today, and we were at the park boundary at precisely 12:11 PM.The storm was epic. It was an atmospheric river storm, a "Pineapple Express" that brought many inches of very warm rain to a snowpack that had fallen only in the last few weeks. Rain was falling at elevations as high as 10,000 feet. The runoff gathered quickly into the streams and rivers, and the Merced went from around 1,000 cubic feet per second to more than 12,000 cfs. Water level at the Pohono Bridge gaging station rose from 5 feet to almost 14 feet. For reference, official flood stage begins at 10 feet, and at 12 feet the main valley roads are covered with water. It could have been a disaster if the valley had been full of tourists.Source: https://www.cnrfc.noaa.gov/graphicalRVF.php?id=POHC1But instead, the weather cleared, and the park service maintenance people worked quickly to clear debris from the roads and bridges. It couldn't have been easy, and there were lots of anxious tourists hoping their vacations wouldn't be totally ruined. They came through, and now you can compare the difference 24 hours can make.Source: National Park Service24 hours ago, clouds obscured the cliffs, and one could barely making out the raging torrents of Upper Yosemite Falls. This afternoon, there was not a cloud in the sky, and while slightly diminished in volume, the falls were as powerful as they will probably be for the rest of the year.Photograph by Garry HayesThe river rose to cover Cook's Meadow, but as the sign shows, nowhere near the level of 1997's even more epic flood. The discharge was twice as high then as it was yesterday, at 24,600 cubic feet per second.Source: National Park ServiceToday the sun shone brightly on a still-flooded meadow, but the water had receded enough that we could follow the boardwalk across the open space.Photograph by Garry HayesI may be posting more pictures soon, but I had to lead off with these since by chance I was standing close to where the photographer was standing yesterday.[...]



Red Fox Family on the Tuolumne River

Sun, 08 Apr 2018 02:09:00 +0000

Be warned: cuteness alert. I was out on the Tuolumne Parkway Trail this afternoon, checking things out after more than two inches of rain in two days. It was sunny and lots of birds were out and about, but just before I got to the end of the trail, I saw something I've never seen before: a fox family.I've seen foxes a number of times over the last three years. One fox that I photographed early on was actually used on the interpretive signs for the trail. I could never figure out from year to year if I was looking at a family or not because I never saw more than one at a time.I haven't seen the foxes for many months now, and I was worried that they might have moved on (silly me). Finally in the last few weeks I've noticed an acrid odor that I suspect was related to the foxes, so I've been watching the grass and shrubs much more carefully. Today, though, I came face to face with the one in the first picture above. I couldn't distinguish the size very well, but I noticed the shorter face and realized it was a pup. A moment later a second head popped up! I didn't get a good shot of both of them at once before they disappeared into their den. It occurred to me that momma must be around somewhere, and then I realized she was in plain sight up on the log above. As you can see in the photos, she was very nervous about me (she could barely stay awake, actually). I've seen momma in previous years; she was wounded in one eye, giving her a distinctive appearanceRed Foxes are one of the most widespread carnivores on the planet, being found across the northern hemisphere. The populations in California are a mixture of native and non-native individuals. The rarest is the Sierra Nevada Red Fox, which is only found in the northern Sierra and southern Cascades at high elevations. It was recently sighted in the vicinity of Sonora Pass, north of Yosemite. The populations in the Central Valley were thought to be escapees from fur farms, but recent work has determined that the valley north of Sacramento has an endemic population. There seems to be little if any information about native Red Foxes in the south valley. There is a native species, the Gray Fox, which I have seen once or twice along the river. There is also the rare and endangered San Joaquin Kit Fox, which I have never seen.I hope I'll have a chance to watch them grow up![...]



Liveblogging the Deluge: Merced River in Yosemite Reaches Flood Stage

Sat, 07 Apr 2018 16:56:00 +0000

This picture is a cheat. I'm not in Yosemite, this picture is from two years agoI was supposed to be in Yosemite right now. We had scheduled a field studies class today that would have sent us up the Merced River to Yosemite Valley and back, but nature has intruded with an unusual April atmospheric river storm that is setting some daily rainfall records across Central California. San Francisco, for instance, received rain equivalent to an average April in a single day. My backyard rain gauge in the Central Valley has recorded 2.2 inches since yesterday. In 26 years of measuring, there have only been three Aprils where we've received that much in the entire month.I had already decided to postpone the trip by last Monday when the forecasts called for flooding on the Merced River in Yosemite Valley. In short, the river jumps its banks at the 10 foot level (about 6,000 cubic feet per second). At 12 feet (9,500 cfs), the flooding river covers some of the main roads in the valley. Today's storm is expected to result in a river that crests at 14 feet, or 14,000 cubic feet per second. Even if I had decided to go ahead with the field trip, we would not have reached our goal, because the park service closed Yosemite Valley yesterday. We're going to try and make the trip tomorrow to check out any flood damage, but if the valley floor is still closed, we'll try to see Hetch Hetchy instead.Yosemite Valley is especially prone to flooding because it is high up in the mountains close to the headwaters of the Merced River, and when rain falls, it falls on mostly barren granite. The water flows into channels very quickly, and the channels gather into the Merced River and Tenaya Creek just as quickly. There are no reservoirs upstream for flood control (nor should there ever be).If it drives home the point, Yosemite Valley has only been closed a few times in its history, most notably in 1997 during the unprecedented floods of that year, and during a few government shutdowns. It takes a major event to convince the park administration to shut down the iconic valley.I hope to be back tomorrow with pictures of Yosemite Valley. We'll see what happens! I will update the flood hydrograph in the space below when the river flow peaks.UPDATE: At 1:00 PM, the river has reached 10,800 cubic feet per second (12.85 feet). If I'm reading the data right (below), this is only the fourth time the flow has reached this level since 1996.Here is the 1:00 PM report: Also, here is a link to video of the main road in Yosemite Valley at the moment, courtesy of the Fresno Bee.UPDATE 2: We've reached 12,100 cubic feet per second as of 5:00PM, and 13.68 feet (10 feet is flood  level), and the flood may be peaking. The discharge only increased by 100 cfs in the last hour.FINAL UPDATE: It looks like the flood has peaked at 12,100 cfs, as it has been there for two hours. I expect it will now start dropping. I'm hoping the valley will reopen in time for our visit tomorrow. If not, I guess we'll check out Hetch Hetchy!WELL, OKAY, ONE MORE UPDATE: Yosemite National Park has posted pictures of the flooding today: https://www.facebook.com/pg/YosemiteNPS/photos/?tab=album&album_id=1650167855031490[...]



An Incredible Spot in the Mojave Desert, the Hole in the Wall. You could see it for yourself this summer

Fri, 06 Apr 2018 07:35:00 +0000

Summer is coming soon. If you are casting about wondering what to do, how about the adventure of a lifetime? Our department is offering a dyad class, Geology 191/Anthropology 191, the Geology and Anthropology of the Colorado Plateau, and it is an incredible chance to check out some marvelous geology along our southwestern tier of states: California, Arizona, Colorado, Utah, and Nevada. I want to give you a bit of a preview of the kinds of places we will be visiting...The Mojave National Preserve is one of our nation's newest parks (established in 1994). It was carved out from Bureau of Land Management lands in the eastern Mojave Desert, preserving one of the most awesome sand dune complexes in the country, the Kelso Dunes, a barren landscape of geologically recent volcanic cinder cones, one of the largest Joshua Tree forests in existence, and some of the highest mountain ranges in the Mojave Desert, with rocks as old as 1.7 billion years old, as ancient as those in the bottom of the Grand Canyon. The preserve also encompasses a California State Recreation Area, the Providence Mountains, and Mitchell Caverns, a unique limestone cave system. The caverns were closed during the recession, and then severely vandalized, but they have finally been reopened for visitation (see this Facebook page for updates).One of the most interesting corners of the park is called Hole in the Wall, along with Banshee Canyon. We will be staying at the nearby campground our first night on the road on June 2. It is a wonderfully isolated spot, 25 miles off the main highway, and even farther from developments of any kind. It has some of the darkest night skies I've ever seen, and it is serenely quiet (except for crickets and coyote yowls).The region is quite unlike other parts of the Mojave. Instead of deeply eroded mountain ranges and wide flat valleys, the area around Hole in the Wall is composed of mesas and plateaus that seem to share more in common with the Colorado Plateau province just to the east. But these mesas aren't like Arizona's either. They are composed not of sedimentary layers, but of volcanic tuff, rock derived from unimaginably huge volcanic explosions the likes of which modern humans have never experienced.Twenty million years ago, the region was one of low relief, the result of tens of millions of years of erosion and relative stability. But conditions were changing as the crust was stretched and broken up into a series of tilted fault blocks. The release of pressure on the underlying mantle allowed partial melting to take place, and volcanic activity exploded across the region.The first eruptions took place about 18.5 million years ago when the Peach Springs tuff coated the entire region from an eruption center near Oatman, Arizona. The eruption involved as much as 150 cubic miles (640 km3) of powdery white ash that was so hot that in many places it welded into solid rock as it landed. Shortly afterward (in geologic terms anyway, as it was 700,000 years later), a second caldera developed. It was located even closer, in the adjacent Woods Mountains. The eruptive "crater", actually a collapse pit, was about 5-6 miles across, roughly similar in size to Crater Lake. Once again, all life was obliterated for hundreds of square miles as hot ash blanketed the landscape. The Wild Horse Mesa Tuff makes up most of the rock found at Hole in the Wall.The strange holes that gave Hole in the Wall its name are called tafoni. Small differences in the degree of solidification or cementation cause depressions to form which end up staying wet longer, and the minerals decay into small fragments that can easily wash or blow away.A short trail (1.5 miles) loops around Banshee Mountain and explores the best of the eroded tuff. Starting at the small visitor center, the trail drops through a rugged narrow canyon. There are some drop-offs[...]



The Most Extraordinary Landscape on Planet Earth: Geotripping on the Colorado Plateau, June 2-17, 2018

Thu, 05 Apr 2018 00:15:00 +0000

North Rim of Grand Canyon National ParkThere is no place on this planet like the Colorado Plateau. It's hard to find anyplace else on Earth where the crust remained relatively stable for upwards of a billion years, accumulating several miles of horizontal sediments, only to be lifted up rapidly in the last few million. The Colorado River and her tributaries then stripped away much of the sedimentary cover, and cut deep into the underlying metamorphic rocks. Those metamorphic rocks record a violent geologic history of colliding landmasses and mountain-building. The resulting landscape is one of the most beautiful places imaginable.Angels Landing Trail in Zion National Park, UtahThe plateau country is a training ground for geologists and earth scientists, and has been since the days of John Wesley Powell and Joseph Ives, who were the first to lead research parties into the region (they didn't "discover" the plateau, of course; Native Americans have known the region for thousands of years). If you are curious about learning geology in this incredible region, you might consider joining us as a student (of any age) on our geology field studies course Geology 191, offered under the auspices of Modesto Junior College in Modesto, California. The course is designed to fulfil the curiosity of lay geologists and archaeologists, but also to build the skills of geology and archaeologists as well.Goosenecks of the San Juan River, UtahOur field course will be a grand loop through the plateau country, with investigations of the Mojave National Scenic Preserve, Grand Canyon, Zion, Bryce Canyon, Arches, Canyonlands, Capitol Reef, Black Canyon of the Gunnison, Mesa Verde and Great Basin National Parks, as well as many monuments, including Bear's Ears, Grand Staircase-Escalante, Natural Bridges, Navajo, Hovenweep, and Colorado National Monuments. It will be an unforgettable two week trip from June 2-17, 2018, beginning and ending in Modesto, California. Information can be found soon at my school website at http://hayesg.faculty.mjc.edu/Geology_191_Colorado_Plateau.html .Black Canyon of the Gunnison National Park in ColoradoIt's not a comfortable trip...we travel in school vans (which of course are known for their luxuriousness!), we camp every night, and the days can be hot, windy, cold, or stormy, and we are out in the middle of anything that happens. But we are staying in beautiful places each night, and there are even showers and laundry available every third day or so! Extensive hiking is not required, but there will be many chances to explore the trails in each park and monument.Double Arch in Arches National Park in UtahGeology 191 is a 3 semester unit course which will be taught as a dyad with Anthropology 191 (also 3 units). By end of the course, you will be able to see the landscape the way geologists do: by identifying rocks, minerals and fossils, and interpreting the geological history of an area by working out the sequence of events as exposed in outcrops. If you are a science teacher, you will come home with a collection of photographs that illustrate most of the important principles of geology, and a selection of rocks, minerals and fossils that will make a great classroom teaching tool (legally collected, of course; there are many localities outside of protected parks from which to collect samples). The dual nature of the course means that you will also have a mastery of the archaeology of the plateau region, the home of the Ancestral Puebloans, the Fremont people, the Navajo, the Utes, and others.Canyonlands National Park, UtahThe cost of the trip will be $850.00 plus the cost of tuition (Currently $46 per unit for California residents, and $222 per unit for out-of-state residents). The cost includes transportation, food, camp fees, and entrance fees. Participants would want to bring[...]



A Shaggy Sheepdog Story for an April Fool's Sunday

Mon, 02 Apr 2018 07:27:00 +0000

This was just a little fun I had today, although I had a moment of worry, wondering about the wrath of a wary guard dog. We've visited the San Luis National Wildlife Refuge several times in the last few weeks. The refuges seek to maintain an environment conducive to the survival of the native birds and other animals of the Central Valley. Unfortunately over the years, many of the native species have disappeared or have been displaced. This is especially true of the big grazers. The valley once hosted mammoths, mastodons, bison, horses, camels, and pronghorns.So the rebuilding of the natural grasslands involves returning native species of grass, and to the extent possible, the return of larger grazing animals. The managers will often allow the limited grazing of the prairie by domestic sheep and cattle. We've been seeing a herd of sheep on our recent visits. We haven't seen the human shepherds, but we've noticed the herd's protectors: some rather large sheep dogs. I think they are a breed called Maremma or Great Pyrenees.And the sheep do need protection. Their natural defensive nature has been largely bred out, and they don't really know how to face down predators like the coyotes we've seen in the vicinity of the sheep herds.So, we were there again today, enjoying the beautiful spring weather and the birds, and even a few newly born lambs in the sheep herd. We got to the southeast corner of the Waterfowl Auto-tour, and found out that the sheep dogs recognized us as a possible threat to the sheep. They actually jumped a fence, slogged through an irrigation canal, and loudly barking and growling, chased our car down the road to the Souza Marsh. They finally seemed to lose interest and fell behind. We parked and I walked around for a few minutes. Then I turned to walk back to the car...and came face to face with a very large sheep dog! Those crafty little beasts had snuck up on us and had me trapped in the open.I actually got bit by a panicked dog a couple of weeks ago, so I was painfully aware of what a dog bite can feel like. I was more than just a little nervous. Luckily, Mrs. Geotripper was already in the car, but I was frozen in place. I finally realized they weren't barking, just watching. I walked slowly to the car. The dogs allowed me to get in the car without making a sound. And then: they herded us out of the marsh and away from the sheep flock, with one dog on either side of the rear of the car. Not a growl or a bark between them. They walked us almost a quarter mile in a highly disciplined manner. I fear for the well-being of the coyote who decides to go up against them.So, there you go for an April Fool's Day, a shaggy dog story, but without the painfully stupid pun at the end. At least none that I could think of in the spur of the moment.[...]



In the Red HIlls Area of Critical Environmental Concern, a Promise of Spring (and a rare fish)

Sun, 01 Apr 2018 07:39:00 +0000

We saw exactly two poppies blooming. In a few weeks there will be thousands.It has a clumsy name that only a bureaucrat could love, but the Red Hills Area of Critical Environmental Concern is a fascinating place in the Sierra Nevada Mother Lode. It was for decades a sullied hidden treasure, used for dumping and target shooting. But as biologists and geologists started to study the region, they found a unique biological island in the normally oak-studded woodlands of the Mother Lode.The uniqueness of the area was tied to the underlying soil, developed on the serpentine and ultramafic rocks of the Foothills Terrane, slices of the ocean crust and rocks from deep in the Earth's mantle that had been added to the western edge of North America some 200 million years ago. Serpentine soils lack many of the nutrients required by "normal" plants like grass and oak, but are loaded with metals that are actually poisonous to plants as well. Plants that survive in this strange other-worldly land have to be tolerant of this harsh chemical environment.  Some of them are very rare, and a few are endemic, found nowhere else in the world. Because of the prevalence of iron, the soils are usually a deep reddish brown, giving the hills their name.This was the single Monkey-flower we found. There will be many more!The delineation is sharp. When one turns off of LaGrange Road onto Red Hills Road one sees oak woodlands and open fields thick with grass. But only about a mile in, the oak and grass suddenly give way to Ceanothus shrubs and Gray Pine. Grass is almost nonexistent, with various flower species making up the ground cover. Much of the year the ground cover is dead and dry, but for a few weeks in the spring, the hills burst into color, and there is a spectacular show of wildflowers, dominated by Monkey-flowers and Poppies.February was an incredibly dry month, no doubt delaying the onset of the spring flower show, but the heavy rains of March have left the soils wet, and sprouts are popping up everywhere. We were there today to look things over, and we could see that land is about to burst forth in another week or two.I wandered over to the creek to see if the fish were around. The Red Hills host a rare and endangered subspecies of the California Roach, the Red Hills Roach (Lavinia symmetricus). The fish were for a short time thought to be extinct when the extended drought dried up the intermittent creeks that they called home. But a few spring-fed pools persisted during the driest times, and the fish are doing okay.They were in a frenzy of feeding or breeding, or just doing some heavy partying when I found them. I caught some video below. All in all, life is returning in the foothills during these brief weeks before the hot dry times come again all too soon. Happy Easter, all! allow="autoplay; encrypted-media" allowfullscreen="" frameborder="0" height="315" src="https://www.youtube.com/embed/umdp2EcWR4s" width="560">[...]



Liveblogging the Deluge: 2018 Short Version

Tue, 27 Mar 2018 05:45:00 +0000

High water on the Tuolumne River, February 2018, about 15,000 cubic feet per second.Why "short"? What deluge? Hasn't this been another dry year?Tuolumne River on January 19, 2018, flow at about 300 cubic feet per second.If you've been reading over the last year, you would know that I started what I thought would be a short blog series (Liveblogging the Deluge) on what looked like (and almost was) a record-breaking atmospheric storm that hit California last January. The storm hit, and then there was another. And another. Prodigious amounts of snow and rain fell in central and northern California through the end of April, putting an end to California's historically bad five-year drought, and filling the state's dry reservoirs. So much snow accumulated in the drainage of the Tuolumne River that the main reservoir, Don Pedro, was constantly at the edge of overflowing, so the outflow was maintained at near flood-level (averaging 9,000 cubic feet per second, briefly to 15,000 cfs) through July. We really had no chance to see the changes on the floodplain until September.Tuolumne River on March 25, 2018, flow at about 4,500 cubic feet per secondAnd then...when the "storm door" was supposed to open in November, barely anything happened. My backyard gauge told the story: October, 0.07", November 1.15", December 0.0". January finally brought an almost normal amount, 3.44", but the next month was one of the driest Februarys ever recorded, with my gauge recording a mere 0.37". Statewide, the snowpack was a mere 20-25% of normal. At Don Pedro Reservoir, there was a lot of water in storage, but realizing that there would be almost no snowmelt, the operators kept the outflow into the lower Tuolumne River at very low levels, about 300 cubic feet per second. They left a minimum of space for emergency flood control.Tuolumne River, January 19, 2018, flow at 300 cubic feet per second.And then March happened. The storm door opened in a big way, and three major storms blew through the state raising havoc with floods and mudflows in numerous localities, including some of the areas affected by the horrific fires of last summer (and December, unfortunately). Locally, we received 3.36", but my little town was one of the driest spots in the state. The snow in the Sierra Nevada was measured in feet, including 7-8 feet in a few places.Tuolumne River on March 25, flow at 4,500 cubic feet per second.It wasn't a drought ending month, but it took the snowpack from disastrous to merely disappointing. Current levels range from 44% to 66% of normal. And now the operators at Don Pedro Reservoir can expect some runoff amounts that will be semi-normal. That means they'll need a bit more reservoir space....I noticed the first ramping up of river flows about a week ago, when the discharge was tripled to about 1,000 cubic feet per second. I could hear the river again (the velocity of the water at 300 cfs is very low). But then when I walked the river trail yesterday, the river was raging along at 4,500 cubic feet per second. Not a flood, but a higher level than at almost any point during the entire run of the 2012-2017 drought. The islands and gravel bars that were being used by fisher-people and picnickers were once again underwater. The slough at the west end of the Parkway Trail where I walk was once again flowing. This is good on a number of counts: salmon and other fish will have a better chance of survival and getting to the sea, and the invasive weed river hyacinth will probably not gain root in the upper areas of the river. The river weed choked the slough and parts of the river channel during the drought, smothering out other vegetation, and making life difficult for fish and aquatic wildlife.Farther afield, the outlook is reasonab[...]



The Rise of the Turtles and a Flat Earth: Musings on Science and Death Valley

Fri, 23 Mar 2018 04:52:00 +0000

One of the ominous turtles rising from the crust in Death ValleyI've been dismayed to say the least at how gullible Americans have become, in so many ways. We could of course get mired in a discussion of politics, or charlatans in religion, but my real concern on this particular day is over the resurgence of flat-eartherism in current pop-culture. A couple of singers and basketball players made waves recently by looking towards the horizon, and deciding all on their own that the Earth must be flat because that's how it looks. All of that "stuff" about NASA and satellites and moon missions are, in their view, hoaxes.Draw closer if you dare...I imagine there are many reasons for this, but a large part of the problem has to do with a pushback against "authority" in society these days, with an increasing lack of trust in government and social institutions like the traditional media and religion. In a number of cases, the mistrust has been earned, but unfortunately science and scientific knowledge have ended up being lumped with the other "authorities" even though the concept of authority in science is different from the others. The authority of science is based on observation and research and has a systematic way to weed out false "facts" from objective truth (it's not perfect, of course, but the structure tends to be self-correcting over time). Unfortunately, with the decline of science education at many levels of public and private education, the distinction has been lost in some quarters. As a result, science becomes another of the buffet of human ideas that can be believed or not believed as one wishes. The consequences will be (and indeed already are) tragic. We have a government, the only one in the world, that doesn't "believe" in climate change. It doesn't think health will suffer if we allow untested or poorly tested toxins into the environment, or if we allow increased air and water pollution. Science is taking a back seat to profit, and people will suffer and die for it. If the voting population is ignorant of the issues, and ignorant of how science works, the abuses will continue unabated.This has led to an interesting exercise I like to do with my students. We introduce how the scientific method works (make observations, collect data, devise hypotheses, test the hypotheses, and if fully supported, designate a theory). Then we do a mind game where we place ourselves in our home here in California's Central Valley a few thousand years ago, with the knowledge and technology of the time. What would the shape of the Earth be from that point of view? There are different layers in the answers to such questions.The first-order answer is "of course the Earth is flat". One merely needs to look around the exceedingly flat Central Valley to see that this is true. It is an explanation that works for everyone concerned and has no serious impact on their daily lives.But there is a second-order observation to be made. A curious person might climb a local mountain and note that with the wider view that the mountain ranges in the far distance seem to disappear over the horizon (or they might see that ships disappear over the horizon at sea). The realization emerges that the world isn't as it seemed. It is dome-shaped! This new truth has implications. A flat earth offers no reasons for disasters such as earthquakes and floods such as those experienced by the inhabitants on the valley floor. So a model is proposed to explain the observations (dome-shape, earthquakes, floods): it is suggested that the earth is actually...on the back of a gigantic turtle. When the dust clears, the analyses and arguments can begin. Turtles that we observe don't move very often, and the larger the turtle[...]



Mrs. Geotripper Faces Down the Wolf: Musings on the Canids of the Great Valley

Mon, 19 Mar 2018 08:00:00 +0000

Note: I know this is a coyote, not a wolf. But read on to see why I used the termThey've always been here.They've always been here, even though we declared war on them, and have tried to exterminate them out of existence. No doubt they're been preying on our chickens, our sheep, our calves, or whatever, but they were here first and we were the interlopers, the invasive species. We came and plowed under the prairies and river floodplains that were the ancestral homes of these creatures.Photo by Mrs. GeotripperThey've been here ever since the prairie rose from the sea sometime in the last 10 million years. At that time, volcanoes still erupted at the crest of the Sierra Nevada, sending lava flows and volcanic mudflows (lahars) down the western slope. The rock layers today are called the Mehrten Formation, and those rocks are the focus of a study published this week by among others, my colleague at CSU Stanislaus Julia Sankey, and a former student of mine, Jake Biewer. They were looking at the fossil canids reported from the Mehrten, and their work shows that the ecosystem at that time included at least four dog ancestors. There were two borophages (a primitive "bone-crushing dog" that is now extinct), an ancestral fox, and Eucyon davisi, a canid that is considered to be an ancestor of today's coyote.During the ice ages, the ecosystem was dominated by Dire Wolves and Sabertooth Cats, but fossil discoveries show that the coyote was present as well 700,000 years ago. The big wolves and sabertooths could attack and take down the large grazing animals of the time, the camels, horses, and bison, but there was always a place in ecosystem for the smaller predators that could live on rabbits, rodents, and large birds.At the end of the last ice age (or with the arrival of humans; there is a debate), the megafauna, the large grazing animals like the bison, the mammoth, the camel, the horse, and the sloth went extinct. Deprived of their prey, the large cats and Dire Wolves also disappeared into oblivion. But there was always a place for the coyote, and they prospered in the newly changed world. As humans moved into their environment, they adapted, and have continued to survive despite the war against them waged by ranchers.So this thing happened today. Mrs. Geotripper and I were doing something we love, exploring the local wildlife refuge (the San Luis National Wildlife Refuge Waterfowl Auto-tour). We were looking for birds as we usually do, but I had just seen the article about the canids, and so I was also watching the prairie for coyotes (or foxes, I wasn't being choosy). And we saw one! It was wandering the grassland, and stayed close enough that we got pictures and video (below). We drove on. Towards the end of the auto-tour there is a hiking trail to a viewing platform. We got out and walked the trail.Mrs. Geotripper and I have opposing methods of seeking birds. I like to cover as much ground as possible, constantly moving, while she prefers to remain stationary, letting the birds come to her. Both strategies work for us, and we usually get a different set of bird discoveries. So it was that she was situated on a folding chair at a bend in the trail, and I was a quarter mile away at the viewing platform. We were sort of nonplussed at a sign at the trailhead warning of Mountain Lion sightings, but we had phones so we could stay in touch.I was up on the platform and was startled, yet pleased to see a coyote go loping by at a fast pace. I'm not even sure it saw me, because it never looked my direction. I snapped some pictures, including the ones above and below, as well as the opening picture at the top of the post. I paused and realized the animal was hea[...]



All My Faults are Normal, But Not Really: Travels in Death Valley

Sat, 17 Mar 2018 06:58:00 +0000

Death Valley is the ultimate expression of the extensional forces that have ripped apart the crust of the western United States. The affected area reaches from northern Nevada and Oregon, east to central Utah, and south into Arizona. The broken up crust has resulted in the formation of countless fault basins and high mountain ranges (the entire region is called the Basin and Range Province). But few of those basins (really just one, the Owens Valley) approach the grandeur of Death Valley.The valley (which is just part of the larger national park) is more than a hundred miles long, and it's deep. The vertical distance from the summit of Telescope Peak to the valley floor at Badwater is more than two miles (11,331 feet). Few places in America display greater relief. And the valley was not carved by water or any other erosional force: it is the result of faulting, the movement of the crust of the earth.Most students of geology are taught early on that fault valleys are called grabens, and that they are formed by normal faulting. That begs the question of "what is normal?" (a concept I'm sure we all struggle with). Faults displaying vertical motion often have a sloping fault plane, and the fault block that "hangs" over the other is called the headwall (which therefore covers the footwall). When the crust is stretched, or extended, the headwall drops relative to the footwall, and that is what defines a "normal fault". If the crust is compressed, the headwall will move up relative to the footwall, forming an "abnormal fault"...no wait, that's my bad joke from the classroom. It's called a "reverse fault".Death Valley is in an isolated lonely region, except for the main tourist area, which lies mostly along Highway 190 and Badwater Road which leads to...Badwater. But Badwater Road doesn't end there. It continues on to the south end of Death Valley and eventually over Jubilee Pass to the village of Shoshone. Few tourists ever venture this way. But there are things to see out there in the deep desert.There is an odd little hill on the floor of Death Valley at the south end near the Ashford Mill (the remains of an old mine). It's a cinder cone, a small eroded pile of volcanic cinders and bombs that erupted tens of thousands of years ago. It's out on the valley floor in the midst of the alluvial fans, made up of the gravel and sands eroded from the surrounding mountains. The short climb from West Side Road provides a fine view of the graben of Death Valley. It's odd because it may be the only mountain you will ever climb whose summit is below sea level (-73 feet to be exact).There are other reasons it is odd. Being in the middle of the valley, there seems no obvious way for lava to reach the surface of the valley. For another, it's in pieces. One half can be seen in the photo mosaic below.From the main highway (below) it becomes apparent that the two pieces are offset from each other. It's been torn apart by faulting, but not by the kinds of faults we looked at above. The side are moving laterally. This kind with the lateral motion is caused by shearing and is called a strike-slip fault. The presence of the fault provides an explanation for the presence of the cinder cone (the magma was able to follow the fault fracture to the surface). But what are strike-slip faults doing in the Death Valley graben?There are two kinds of strike-slip faults, right and left lateral. The type can be determined by looking at what the opposite block has done from the observers position: notice below that Pokey moved to Gumby's right. But from Pokey's point of view, Gumby has moved to Pokey's right. That's a right lateral fault.One can therefore see t[...]



Waves on Fire at the Devil's Slide near Half Moon Bay

Mon, 12 Mar 2018 05:44:00 +0000

Even though Geotripper is a geology-based blog, it seems ocean waves don't make an appearance all that often in my posts. Try as I might, I don't photograph them very well, or very creatively. I love them, however, and can watch them for hours at times.I think part of my difficulty is the point of view. Most of the time we are standing on a shoreline and the waves crash in front of us, always with the curl of the impending breaker, and the swash upon the sand beach. Always the same angle. And that's what caught my attention tonight. We had occasion to be in Half Moon Bay at sunset, and it was a truly beautiful splash of color in the sky. We had finished dinner at Miramar, where the coast is a long curving stretch of sand. Certainly pretty, but we wondered what the sunset would look like from a bit higher...like hundreds of feet higher. So, as the sun sank closer to the horizon, we headed north on Highway 1, and soon reached the new tunnels at Devil's Slide.The Pacific Coast Highway was meant to hug the coast from Mexico to Oregon, and the effort to complete it was monumental. Regrettably, almost all of California's coastal cliffs bear the scars of road construction, and only about 25 miles of the state's spectacular shoreline remains as true wilderness. Just the same, there is no experience quite like following this highway from one end of the state to the other. It begins in the nightmare of urban traffic throughout most of Southern California, leading to winding mountain roads through immense Redwood forests in the north. Of all the spectacular stretches of highway, the one between Half Moon Bay and Pacifica has given road engineers the biggest headache of all. It's called the Devil's Slide.The highway was built over an active landslide hundreds of feet above the shoreline. From the very beginning, the road experienced constant damage from slope failures, and the highway was often closed for expensive repairs. The powers-that-be finally gave up and eventually built the Tom Lantos Tunnels through the mountain behind the slide and closed the old highway in 2014. It was given to the county and is now operated as a trail and scenic overlook.That's where we found ourselves tonight at sunset: hundreds of feet above the shoreline looking almost straight down on the crashing waves. I realized I was seeing something unique, the waves from above, with the dramatic light of the sun on the backside. It was an indescribable sight, so I won't even try. You'll just have to enjoy the pictures.I've included a couple of pictures of the broader view so you can have some context for understanding the pictures above.The waves are rolling into a narrow cove, and break as they reach shallow water. The shore is mostly bedrock with no sand, so as the waves break, they often reflect (bounce off the water's edge) and roll backwards, breaking again against the other side of the cove. The intersecting waves create an interesting tapestry.Despite the imposing name, the Devil's Slide is one of the most spectacular stretches of the California coast, and is not to be missed if you ever find yourself in San Francisco. It's no more than 30 minutes from downtown or the airport. I've often visited there while waiting to pick up people from the airport.[...]



How Low Can You Go? Badwater Basin, and a Real Hell on Earth

Sun, 11 Mar 2018 07:06:00 +0000

Salt flats at Badwater, -282 feet. The snowcapped mountain in the distance is Telescope Peak, 11,049 feet. How bad could it be? On our recent trip to Death Valley, we made the rather mandatory pilgrimage to Badwater, the lowest point in North America at -282 feet (86 meters). Although the hottest temperature ever recorded on planet Earth was measured at Furnace Creek Ranch in 1913 (56.7°C; 134°F), it is known that Badwater is often 2 degrees hotter. That's hot. Really hot.I've regularly worked and played in temperatures as high as 105°F without ill effect at home in the Great Valley of California. I floated down the Colorado River in August of 2013 where temperatures soared as high as 118°F, and I realized that I could have been in trouble if we didn't have the river to dip in every few minutes (because it flowed from deep within Lake Powell, the water temperature was around 48°F even many miles downstream). The hottest moment I've ever experienced was in the aforementioned Death Valley when we had an occasion to be there in late May, and an early heat wave shot temperatures to a near record 122°F. It was simply intolerable outdoors...we retreated to the motel room until the sun went down before emerging to seek dinner. People no doubt adapt to such conditions, but it can't be pleasant.Alluvial fan just south of Badwater. The terraces on the fan are fault scarps, indicating the role of faulting in the subsidence  of Death Valley.Standing at the lowest point in North America does cause one to consider other low places on the planet. The National Park Service provides a handy guide on interpretive signs and on their websites. They note that all of the low places also tend to be exceedingly dry and hot, and that the source of the low elevation is generally tectonic in origin. Those low points are as follows:Dead Sea (Jordan/Israel) -1360 feet (-414 m)Lake Assal (Djibouti, Africa) -509 feet (-155 m)Turpan Pendi (China) -505 feet (-154 m)Qattara Depression (Egypt) -435 feet (-133 m)Vpadina Kaundy (Kazakstan) -433 ft (-132 m)Denakil (Ethiopia) -410 ft (-125 m)Laguna del Carbón (Argentina) -344 ft (-105 m)Death Valley (United States) -282 ft (-86 m)Vpadina Akchanaya (Turkmenistan) -266 ft (-81 m)Salton Sea (California) -227 ft (-69 m)Sebkhet Tah (Morroco) -180 ft (-55 m)Sabkhat Ghuzayyil (Libya) -154 ft (-47 m)Lago Enriquillo (Dominican Republic) -151 ft (-46 m)Salinas Chicas (Argentina) -131 ft (-40 m)Caspian Sea (Central Asia) -92 ft (-28 m)Lake Eyre (Australia) -49 ft (-15 m)The Black Mountains provide the backdrop to Badwater. They rise steeply more than a mile above the salt flats.Looking at this list, it is clear that the Dead Sea is in a class by itself as far as low elevations are concerned. At nearly 1,400 feet below sea level, it is unique in the world. To find anything deeper, we have to reach back into the depths of geologic time. The Strait of Gibraltar is narrow and shallow, and is the only connection between the Mediterranean and any other ocean. What would happen if it ever separated the two oceans? It's not totally idle speculation...it turns out that this actually happened, about six million years ago. The speculation began when vast amounts of salt, gypsum and anhydrite deposits were discovered beneath the seafloor sediments of today's Mediterranean Sea.When the cutoff occurred, the Mediterranean immediately began to dry up. And dried more. And then even more. The level of the sea dropped precipitously. It dropped past the 1,000 foot level. And then 2,000. And it kept going. Until the level of the basin reached 15,000 feet below sea level. [...]



Yosemite's Half Dome Makes an Appearance...in the Central Valley

Thu, 08 Mar 2018 07:57:00 +0000

Once a week, my errands take me past the intersection of Keyes and Hickman Road on the floor of California's Central Valley. There is usually nothing much to be seen there in the late afternoon hour, just some fields of crops and almond orchards. Nothing much that is, except for the rare clear days in our usually smoggy and dusty valley. On those days, the Sierra Nevada can be seen off in the distance, and from a narrow angle, one can see the looming edifice of Half Dome, rising 4,000 feet above Yosemite Valley. Today was one of those days.It's been a little controversial, because there are some who think it is not possible to see the dome, and indeed it is not easy to see unless you know just where to look. My pictures are at zooms ranging from 60x to 120x. The picture below provides an idea of the appearance with the naked eye. The dome itself is mostly to the left of center. One has to keep in mind that the rock is something like forty miles away, and there are even effects caused by the curvature of the earth that make it look odd.The previous day had been clearer, but I just couldn't get away to try for the picture. I had to sharpen the contrast and play with the other settings to bring out the dome. Some are surprised that it doesn't form the skyline, but the peaks behind reach elevations of 12,000 feet or more. Half Dome isn't even 9,000 feet high. I only discovered the view because the first time it was visible to me, there were clouds obscuring the peaks behind, causing the dome to stand out as if it were on the skyline.We'll see if the storms next week clear out some of the dust and smog...[...]



The Struggle for Life in a Harsh Desert: The Living Fossils of Fossil Falls

Wed, 07 Mar 2018 03:26:00 +0000

Fossil Falls, the Bureau of Land Management site near Little Lake and south of Owens Valley, is one of the strangest sights in the California Desert. The ironic point of Fossil Falls is that it has neither fossils, nor does it have falls. It is the former path of the glacial ice age Owens River where it drained Owens Lake and spilled over into China Lake Valley. The river was quite vigorous in its time, and carved a fascinatingly complex waterfall complete with giant potholes. But except for the occasional rill formed during rainstorms, the falls have been dry for thousands of years. I've written about the falls at length several times over the years (check out a sampling by clicking here).But that's not what I wanted to talk about today. I want to talk about something I know practically nothing about (that's my right as a blogger!!). Every time we stop at Fossil Falls and the students are exploring the labyrinth of potholes and drop-offs, I am on my belly staring at a small hole in the lava flow. What could possibly be more interesting than volcanism and glaciers and faulting and the Sierra Nevada?Well, nothing actually. But after visiting the site for thirty years, some other things can capture my attention...such as a desperate struggle to survive in a horrifically harsh land. In the small crucible of an insignificant pothole, an entire ecosystem has been born, and has only days to grow to adulthood, reproduce, and then die. The players are small arthropod shrimp, and maybe ostracods (seed shrimp).Arthropods were one of the earliest forms of complex multi-celled life to leave a rich fossil record. Trilobites (the fossils of which we will see in a later post) account for around three-quarters of all of the hard-shelled fossils in rocks from 530 million years ago. The arthropod phylum, which includes the insects, spiders, scorpions, crabs, lobsters and many others, is the most successful lifeform ever to inhabit Earth, both in terms of biomass and in diversity. Arthropods are found in the deepest coldest oceans and in the hottest of rainforests. But one might expect that the desert would defeat them, especially those species which have gills, and thus must live in water to survive. But here at Fossil Falls there are creatures that have adapted to the severe climate. Their secret lies in patience and speed.Desert Shrimp and Seed Shrimp (or Ostracods?) in close up.I'm always struck by how these small creatures cling to life in their exceedingly small habitat. They are the extreme example of how life finds a way even in the most difficult of circumstances. No water most of the time? Evolve a way for the species to survive desiccation even if an individual cannot. Water for only a short time? Evolve rapid maturing and reproduction. Long periods of drought, possibly lasting for years? Evolve eggs (or cysts) that can last for years without water. These tiny beings can show a direct line of ancestry to the first arthropods in Paleozoic seas 540 million years ago, but they are very different creatures now.These little creatures are actually bivalves in the manner of clams, but they are far different. The unfortunate ant provides scale.I admit to not knowing very much about the species of creatures found in this hole, and an internet search didn't yield very much information. I hope my biologist readers can shed some light on the identities of these creatures. I will gladly add the info to this post. As best I can tell, the larger animals (below) are called Desert Shrimp. The extremely small yellow creatures seem to be [...]



The Sounds of Science (with apologies to Paul Simon): Kids are More Talented Than You Think

Sun, 04 Mar 2018 22:50:00 +0000

Strange things were afoot on Saturday at Modesto Junior College, where I've been teaching for the last thirty years. There was a Tyrannosaur flipping burgers, and a very cool Triceratops taking orders for Brontoburgers and Raptor dogs.There was a constant barrage of earthquakes recorded on our seismometer upstairs on the third floor. There was some sort of harmonic tremor going on, visible on the bottom row of the monitor below. Was a volcano about to erupt under our campus? Were we in the grips of an earthquake swarm? Nah, nothing like that. It was instead that time of year for the sounds of science to take place at our institution: the Science Olympiad.Forty-six junior- and senior-high schools from Stanislaus County, many hundreds of students, had gathered to compete in a series of science-related events. The winning schools from our competition would advance to state-level competition.Our county is economically moribund. It takes a long time for economic recoveries to reach our region, which regularly has an unemployment rate that is twice the national average. Recessions hit us first (we reached close to 20% unemployment in 2011). The money for education is limited to say the least. And it often seems that science is not a very high priority when budgets are proposed. But the funny thing is, our residents have better priorities than our political leaders. When we had a chance to vote for a bond issue to upgrade our community college campus, including the construction of a Science Community Center, the county voted for it. Since the center opened in 2015, with the planetarium and the Great Valley Museum of Natural History, tens of thousands of kids (and their parents) have paid a visit. Our county knows that support of science is a key to a secure economic future.And so we witnessed the genius of our best and brightest students competing for glory in laboratories instead of football fields. There were more than forty events. I was in charge of the competition in Rock and Mineral identification, and some of the student teams had scores that rivaled those of my first- and second-year geology students.If you are wondering about why a T-rex and a Triceratops were involved, well, what can I say? 700 or 800 hungry students were on campus, and our Geology Club stood ready to provide them sustenance to help raise funds for our field studies program.I've been participating in the Science Olympiad now for nearly three decades. It is a privilege and an inspiration to see these very talented students in action. It gives me hope for the future.[...]



Seeking the Savanna instead of Seas: "Saturday Night Live" and Geology??

Thu, 01 Mar 2018 07:58:00 +0000

Historical geology is a real head trip (remember that term?). Stick geologists in the desert against a cliff like the one above, and they will make a few observations, pick up a few stones (and/or fossils), and in their mind's eye, they will be exploring a long-ago prairie that would have looked much like the one in the picture below (a bit of the rarest ecosystem in California, the prairie at Merced National Wildlife Refuge).There would be differences of course. This current-day prairie is populated by a diverse group of birds and small mammals like ground squirrels and rabbits. But it lacks some of the components of a healthy modern wild prairie, mainly the larger grazing animals like deer, antelope, and bison, and the large carnivores that would prey on them. Coyotes and foxes still inhabit the region, and cattle or sheep are sometimes brought onto the prairie to help maintain the quality of the grasslands. But the larger canines and cats, i.e. the wolves and the lions, are long gone, as are the bears.We were on the first full day of our exploration of Death Valley National Park. We weren't there yet, because we had a hundred miles of Mojave Desert to cross before we reached the park. Along the way we made a stop at one of California's most spectacular state parks, Red Rock Canyon (not to be confused with the Red Rock Canyon National Conservation Area outside of Las Vegas). Red Rock Canyon is on Highway 14 between the town of Mojave and Lone Pine, southeast of the Sierra Nevada. The place will look familiar to many, as the striking red and white cliffs have formed the backdrop to dozens if not hundreds of Hollywood movies (including some the opening scenes of the original Jurassic Park).The plain hills to the south of our parking area (in the picture above) are composed of Paleozoic and older metamorphic rocks that have been displaced and uplifted along the Garlock Fault just south of the park. The rocks have been moved some forty miles from their original location by the left lateral movements of the fault zone. They have their own fascinating story, but what catches the eye are the much more colorful sedimentary layers that were deposited on the eroded surface of the metamorphic rocks between about 8 and 12.5 million years ago, a time period called the Miocene epoch.For many of our students, this is the first real-world example of the basic principles of stratigraphy. We spent a few minutes talking about the birth of the science of geology in the observations of Nicolas Steno (superposition, lateral continuity, and original horizontality), and James Hutton (uniformitarianism). Then I unleashed them onto the rock exposures so they could evaluate the origins of the rocks and the sequence of events that produced the spectacular cliffs in front of us.Understanding the changes of a prairie ecosystem through time is as easy as understanding "Saturday Night Live" (which for a fact might not be that easy). For more than forty years the underlying structure of the show has remained much the same; there's a guest host, there is a cold open ("It's Saturday Night!"), there are skits, there is the weekend news, there are fake ads, there are musical numbers. But cast is constantly in flux. There have been many people over the years who have filled in the niches: those who could mimic political figures, those who could act as the "straight man/woman", those who could sing. Sometimes the actors were so unmemorable that they disappeared without a trace after a few weeks[...]



Former Seas and Oceans: Searching for the Past in the Great Valley

Thu, 22 Feb 2018 03:01:00 +0000

The world changes. It changes minute by minute as events happen in human society, the disasters, the eruptions (such as Sinabung this last weekend), the wildfires, the earthquakes. Other changes are more incremental, such as the rise of mountain ranges and their removal by the relentless forces of erosion. Given enough time, huge changes take place, but no one in the midst of these processes would ever notice a difference over the course of their lives.Teaching geology and the earth sciences is often a challenge, especially when we talk about the history of planet Earth. The rocks on the slopes before us may look barren and innocuous, but huge events reveal themselves when we start observing them carefully. As a professor at a community college, my students are usually neophytes in the geological sciences. They are seeing the earth from a new never-before considered viewpoint.I was on the road this last holiday weekend, introducing my students to the geology of Death Valley National Park. Some are currently in geology classes, some already had taken my courses, and some were entirely new to the science. Death Valley is a long drive from our campus, so we left on Thursday night to cover the 200 miles of the flat Great Valley, and to get a head start towards the desert. We camped at Kern River County Park outside of the town of Bakersfield, and at the foot of the southern Sierra Nevada.After a cold night, we awoke to a panorama of barren grass covered hills with no rocks in sight. A layer of soil covers them all, except where roadcuts expose a small part. We talked in camp before leaving about how geologists see landscapes. Where a politician might see only city and county boundaries, geologists see provinces, regions with a unique geological history that contrasts with the areas around them. The Great Valley of California, for instance, is a vast 400 mile long trough that has been collecting eroded sediments from the Sierra Nevada and Coast Ranges. It's been going on for at least 140 million years, and the sediments have accumulated to depths as great as 50,000 feet. More recently, perhaps during only the last one or two million years, the land was uplifted and gently tilted, causing the sediments to start eroding again.We further talked about how geologists organize the rocks they see into formations, members, and groups. We recognize that in specific environments (ocean bottom, river floodplain, delta, sand dune) specific kinds of rocks will accumulate, and we can recognize by a change in the rock that the environment changed at some time in the past. In other words, as one looks at a cliff, different layers with different rocks and different colors show how the depositional environment changed, such as a river flood plain being inundated by rising sea level, or becoming drier and changing to a desert with dunes and the like. These unique layers are called formations. Formations are distinguished by being mappable and by having precise definable contacts with other layers above and below. Thinner distinctive layers within a formation may be defined as members, while several closely related formations (such as desert dry lake salt layers and desert sand dune deposits formed adjacent to each other at about the same time) may be classed as a group.At our locality along the Kern River, a shallow seaway once existed. Maybe that's not such a stretch, since a rise of sea level of only 300 feet would inundate the area again. The presence [...]



Geotripper Missing in Action? Nah, Just on the Road.

Wed, 21 Feb 2018 01:54:00 +0000

If you've noticed a distinct lack of blog updates lately, it's not been for lack of creative ideas. I've actually been in the wild hinterlands of the eastern California desert, specifically Death Valley. We had a marvelous time, but we also experienced a bit of the harshness of the "Broken Land" as Frank DeCourten calls it. There's a bit more cellular and Wi-Fi access in recent years for better or worse, (better for emergency situations), but no time when dealing with a group of students (who were great). Besides, a desert night is meant to be experienced, not ignored in favor of a computer screen. The stars were beyond belief.

In any case, the stories will unfold in the next few blogs. There were some incredible sights, and I look forward to sharing them. Today's picture was a camp visitor on our first night of the trip on the Kern River near Bakersfield.



Historical Geology Laboratory in 1930, with a Few Personal Twists

Sat, 10 Feb 2018 08:02:00 +0000

I admit it. I miss a lot. I've noticed that a lot of colleges and universities are very proud of their history and traditions, but in my experience at three community colleges, the memory of a department is rather short. When I started at Modesto Junior College, I was told stories of my predecessor, who was a legendary character, and not in a good way. Although he served for many years, his retirement was welcomed by many. It took a number of years before I found that some rather significant people taught in the position I occupy now, including Richard Hilton, who wrote Dinosaurs and Other Mesozoic Reptiles of California. Another was Charles Love, the son of Wyoming geologist David Love, whose career was central part of John McPhee's excellent book Rising From the Plains. But those individuals only reach back into the 1970s. I've got no idea who was here in the first fifty years of the existence of our institution.Likewise, I know very little about the first college I attended, Chaffey College in southern California. It's true that I was just a gawky teenager who had no sense of institutional history when I was there between 1975 and 1977. I got to know my two professors, but they were relatively young at the time, and I had no sense at all of who taught there in earlier years.So I had a series of interesting revelations tonight. I had known that my step-grandfather had taken a geology class way back in 1930, and it turned out that he held on to some of his notes (present-day students of mine: do YOU do that??). They were passed on to me, and I set them aside and they were "lost" for a time when we had to pack up the entire house for a re-carpeting job (yes, this is obviously a convoluted story). In any case I ran across the notebook again and finally decided to sit down and have a closer look.The first surprise had nothing to do with the geology. I'm sure I was told this but it just didn't register: my grandfather went to the same community college I did! At the time it was called Chaffey Junior College (today it is simply Chaffey College). That "junior" conferred a sort of inferiority upon the students who needed to attend a cheaper local alternative to expensive universities and private institutions. But if there is anything that I've found to be true, it is that we community colleges produce a great many talented graduates who have competed very well when they've transferred to four-year institutions. Still, over the years, California's community colleges have dropped the "junior" from their name...all but two: Santa Rosa Junior College, and my very own Modesto Junior College. We decided a long time ago that we liked our name. Our students provide us all the reputation for excellence that we need.As I opened the lab book (which hasn't changed form in nearly 90 years), a slip of paper fell out. It was his report card. What was great interest to me was that the geology instructor had signed his name, R.D. Dysart. I had found the name of a geology instructor from those early years of Chaffey's history. So I got curious and started searching on the internet for any information about the man (and how unfortunate it is that I immediately and correctly assumed that it was a man?). And with that came the second big surprise.I got my bachelor degree in geology from Pomona College, an achievement for which I am very proud (I'm not saying I excelled; I made it through the program...ba[...]