Wednesday, January 17, 2018

There's Always Something New to be Learned: Beavers on the Tuolumne River

I will freely cop to the fact that I am not a particularly observant person. This is quite an admission for a guy who has been blogging for ten years about geology, the science that requires skills of observation almost like no other. Still, there it is. I lived in Stanislaus County for thirty years thinking that we have maybe twenty species of birds. In the last three years of finally paying attention to such things, I've learned that we have three hundred species, including those which utilize some of the most famous wintering grounds for migratory birds in the American West (if you want to learn more about this, check out my other blog Geotripper's California Birds)

It is along similar lines that we come to my new educational experience of the day. I've been hiking the Tuolumne River Parkway Trail since before it was completed two years ago. I've documented more than sixty bird species on my near-daily hikes as well as the presence of Red Fox, Gray Fox, River Otter, Raccoon, and a troop of feral domestic cats. And yet somehow, in all of these mini-adventures, I missed some terribly obvious evidence of one other mammal along the river. Until today, when it was made as clear as the nose in front of my face...we have beavers.
I've always been aware of fallen trees along the river, but I never thought about why. But today, the cuttings were so fresh and obvious that I had to stop and look, and I did in fact see rippling in the water nearby. I may have actually interrupted the beaver at work (although they generally work at night). I started looking around and noticed that there were plenty of other small trees that had been felled by beaver incisors.

I had to hit the books (er, Google) to find out more. It turns out that the story of beavers in California is both muddled, and complicated. For one thing, California has its own beaver subspecies, including the California Golden Beaver, Castor Canadensis subauratus. Whether the distinction is biologically valid awaits confirmation from DNA studies. There isn't a lot known about their historical distribution because as most students of history know, the beaver was eradicated over much of its range by fur trappers in the early 1800s. It was assumed by some that they never inhabited the High Sierra, although some research has indicated that they did. They may have originally ranged across the entire state except for the deserts, and even there they survive today along the Mojave and Colorado Rivers. In any case, it is thought that by the 1940s there were as few as 1,300 of them left, almost all in the Great Valley. At that time, the Department of Fish and Game decided to transplant some of the beavers into some of their former range. At this point I had another surprise: some of the transplants were taken from the Tuolumne Waterford, the very spot where I was seeing beaver sign for the first time!
Beavers can be pests, especially in places like the delta of the Sacramento/San Joaquin Rivers, where they can cause severe damage to artificial levees. On the other hand, beavers can be highly beneficial in natural (or re-established) riparian habitats. Their dams help to slow down river erosion and allow more water to percolate into the ground. They tend to cause an expansion of the riparian woodlands by widening the area where the groundwater table is close to the surface.
The other small surprise of the day was the discovery that I was not the first to notice the presence of beavers (far, far from it of course). But one of the first hits on Google was that of another frequent user of the Tuolumne Parkway Trail, a naturalist, and erstwhile geology field studies student Siera Nystrom, who has taken several of my courses. Check out some of her excellent writing at Natural History Journal. Whatever I see and get excited about, she probably has seen it first! Being observant is a powerful skill to have.

Tuesday, January 16, 2018

A Look Back at Ten Years of Geotripping: Driving Through the Most Dangerous Plate Boundary in the World

Driving through the most dangerous (kind of) plate boundary in the world is actually not very easy to do. Subduction zones, with the exception of the volcanoes, are mostly deep under the sea. But Central California is a unique case, being an ancient subduction zone that has been uplifted and exposed by erosion, so that interested parties can literally drive through what once was miles underground or at the bottom of the deepest oceans. I got the idea for this blog series when I spent an afternoon driving the winding road that travels over the Coast Ranges at Lick Observatory, and down through Del Puerto Canyon into the Great Valley. It's the equivalent of driving twenty or thirty miles into the Earth's crust. Looking back over the titles, I'm worried that I am using up my lifetime supply of bad jokes...

I've been reviewing the archives this week to find some of my favorite posts from ten years of geoblogging. This compilation appeared on July 4, 2015.

Without a doubt, subduction zones are the most dangerous plate boundaries on the planet. Divergent plate boundaries produce earthquakes and occasional volcanoes, but nothing on the fearsome scale of the calderas and stratovolcanoes and magnitude 9 earthquakes experienced at convergent boundaries. Transform boundaries produce earthquakes, but they are magnitudes smaller than those produced at convergent boundaries (despite what certain Hollywood movies have asserted recently). Hot spots, while not a plate boundary, can produce huge caldera complexes like Yellowstone, but such monsters have not had much of an effect on human history of the last few thousand years. It is the subduction zones of our planet that have caused the most human misery, in the form of massive earthquakes, tsunamis, and violent volcanic eruptions.
We have been driving through an example of one of the most dangerous plate boundaries in the world, but our particular example has been inactive for a very long time. Central California was a subduction zone complex for more than 150 million years, primarily during the Mesozoic era, but it changed into a transform boundary only a few tens of millions of years ago. The San Andreas fault is the resulting feature, and it is capable producing damaging earthquakes, but even the most destructive quakes, like 1906 in San Francisco (death toll 3,000), is but 1/30 of the energy of a magnitude 9 quake like that of Indonesia in 2004 (where the resulting tsunami killed 200,000 people).

It's taken a couple of months to work through our journey, so I've compiled all of the posts here so one can catch the continuity of the story. Here goes...

A New Blog Series
The introduction to the new series, a geological transect from the California Coast to Yosemite Valley, crossing an ancestral subduction zone that once caused geological havoc in a zone from Mexico to Canada (and still is in a few places).


An overview (in the most literal sense) of the lands we will traverse on our journey. We have a look at central California from above.

These Rocks are All Wrong!
Granite is exposed in the rocks of the Point Reyes Peninsula. But the arrangement of rock and sediment in subduction zones suggests that granite shouldn't be anywhere near here. It's the San Andreas fault. In California, it's always the San Andreas' fault.

Looking for the Big One
The peace and serenity of Tomales Bay belies a violent past. The San Andreas fault slices right through the bay, and produces large earthquakes with disturbing irregularity. The epicenter of the San Francisco quake in 1906 was not far from here.

Welcome to Geology's Junk Drawer
The Marin Headlands began as a giant collector of geological flotsam and jetsam from the crust of the Pacific Ocean. The jumble of rocks accumulated in an accretionary wedge, and were later lifted up into the mountains of the Marin Peninsula.

Geology's Junk Drawer on the Marin Headlands
Exploring the hidden corners of the Marin Headlands, we find Redwood forests, beautiful views of San Francisco, and disturbing reminders of World War II.

Terra Fatale on the Marin Headlands
Although the subduction zone that formed the rocks of the Marin has been extinct for a long time, there are still plenty of hazards remaining in the region, both geological and nautical. The Point Bonita Lighthouse has been present in one form or another for 160 years. It hasn't always worked, as there are upwards of 300 shipwrecks in the area. There are other hazards too.

The Alien Bursts Forth in the Diablo Range!
We head across San Francisco Bay and start an arduous journey through the Diablo Range. The range formed as an exotic (read "alien") terrane pushed upwards through the sediments of the Great Valley Group, piercing the surface and rising into the sky. John Hurt would no doubt approve...

Exploring the Belly of the Beast in the Diablo Range
We make the first part of a long drive through a rugged portion of the Diablo Range, one of the largest sub-ranges in the Coast Ranges of California. Along the way we cross through two exotic terranes of rocks that had been carried miles deep into the crust in the accretionary wedge of the subduction zone.

At the Portal of Hell in Diablo Range
Making our way down Del Puerto Canyon in the Diablo Range, we do the equivalent of traveling through the crust of the Earth all the way into the mantle, finding outcrops of peridotite and dunite, rocks containing the mineral olivine among others. For the mercury miners, this truly was a portal to Hell.

Exploring the Ocean Crust without Unobtanium
Del Puerto Canyon cuts a swath through the Coast Range Ophiolite, the remnants of the ocean crust that once lay at the bottom of the Pacific Ocean. Though mostly in private ownership, the canyon is one of the most scenic in the Coast Ranges, and a pair of county parks in the upper reaches invite exploration.

Into the Realm of the Drowning Dinosaurs
Sediments accumulated in a deep trough along the west coast of North America called a forearc basin for upwards of 100 million years. The layers reached a depth of 5 miles! In those waters swam mosasaurs (yes, like in the recent Jurassic World movie, but they forty feet long, not a hundred), plesiosaurs, ammonites, and occasionally a drowning dinosaur. The first discovery of a dinosaur in California happened here in 1936.

The Sea Floor that became the Greatest Agricultural Region on Earth
The American Serengeti is a vast plain 400 miles long and 50 miles or so wide that once was the sea floor. The grasslands of the Great Valley once supported millions of migratory birds and grazing animals. It still supports millions of organisms, but these days, those organisms are humans. 95% of the original prairie has been developed for agriculture and the region produces a quarter of the nation's produce. And all of the almonds and walnuts.

In the Pleistocene, a Different Kind of Danger
The Great Valley would have been a most dangerous region for a different reason in the Pleistocene. Among the great herds of grazing animals there were predators, and they were adapted to bringing down giant prey, not the small game we find today. Gigantic Short-faced Bears, Saber-tooth cats, American Lions, Jaguars, and Dire Wolves.

The Dr. Who of Mountain Ranges
At least three Sierra Nevada ranges have existed throughout time. They might have even once been higher than today. The distorted deformed metamorphic rocks tell the story of the earlier ranges.

A Gentle Landscape Belies a Fiery Past
The Valley Springs formation, exposed throughout much of the Sierra Nevada foothills region, forms gentle grass and oak covered slopes, but the rock is made of volcanic ash that originated in monumental explosions millions of years ago. The ash came from gigantic calderas, some of which were hundreds of miles away in central Nevada.

A Landscape Buried in Hot Mud, and a 6-foot Long Saber-tooth Salmon

A lot of volcanoes in the world are made of mud. Lots and lots of mud. But this mud formed in violence. The Mehrten formation of the Sierra Nevada has other surprises too: gigantic tortoises, and six-foot long salmon...with fangs...

A Tale of Two Subduction Zones
There have actually been at least two subduction zones in California. Remains of the older one still make up the rocks of the Sierra Nevada Mother Lode, and those rocks were the source of gold in the Gold Rush.

Exploring the Underside of the Volcano

We wrap up the series in the heart of the ancient magmatic arc: Yosemite Valley. Walking among the towering cliffs, we are reminded that the rocks were actually formed within the magma chambers of volcanic systems, perhaps similar to Lassen Peak, Mt. Shasta, or even at times, Yellowstone.

Monday, January 15, 2018

A Look Back at Ten Years of Geotripping: I toured a marble quarry on Vancouver Island; It's almost as if they didn't want us to see the rocks.

I've been digging through the archives of Geotripper on the occasion of my tenth anniversary of geoblogging, looking for some of my favorites. In 2015 I spent a lot of time in the Pacific Northwest, resulting in several blog series, but a favorite moment was my tour of this "quarry" which some of you may recognize as something else. This blog appeared on July 13, 2015...

So, I'm out on Vancouver Island, British Columbia, enjoying my vacation with Mrs. Geotripper, and we're casting about trying to figure out what to do on this 300-mile long island. I'm doing some reading and find out that there is this place called the Saanich Peninsula Marble Quarry that offers tours. That sounds great to the geologist in me, so I talk Mrs. Geotripper into checking it out. It turns out that when you are touring an island that is mainly rainforest, rock exposures are in short supply.
I figure that a rock quarry isn't going to have a whole lot of visitors on a given day, so imagine my surprise when we reach the end of the road, and find out that the place has a parking lot, and charges admission! It was pretty steep, too, about $30 Canadian for each of us. But hey, it's rocks, and I haven't seen a lot of rocks on this trip. We pay and go on in. I'm astounded by how many people are here for the tour of the quarry.

I did some research on the rocks. The marble of the Saanich Peninsula is part of the Wrangellia terrane, rocks that formed far out in the Pacific Ocean during the Triassic Period. Around 100 million years ago during the Cretaceous Period the rocks plowed into the west coast of North America and became part of the continent. The rocks were originally limestone that formed in coral reefs and along tropical island beaches. The heat and pressure of the collision with North America caused the rock to recrystallize into marble. Today it is called the Quatsino formation.
So I follow the map, my anticipation rising as we reach the edge of the quarry, and I looked in. I was kind of shocked. There was vegetation everywhere! There was barely any rock to be seen at all! I did notice the smokestack from the smelter almost hidden in the forest beyond the quarry. How could they let this happen? Didn't they care enough to keep the rock exposed for us geologists? 
The hundreds of people around me didn't seem to mind all the vegetation. As far as I could tell, they were actually paying more attention to the flowers and stuff and pretty much ignoring the rock. I was a little confused. But at least the people that run the place have a sense of history. They put up some interpretive signs that showed the raw beauty of the rock before all the vegetation was allowed to grow over it.
The quarry was active from the late 1800s to around 1905 or so. I guess in this temperate rainforest environment the plants can take over pretty quickly. I was kind of surprised by how colorful the flowers and other plants were. I thought that at this latitude, the species diversity was on the low side. I guess not.
I finally found some rock exposures at the lower end of the quarry. The flowers hadn't yet covered everything. Water had filled the lowest part of the quarry, and I guess they were using a fountain to aerate the water or something.
It's almost as if they were ashamed of the rocks. Look at the picture above to see how the plants covered almost every part of the marble. I just didn't get it. In any case, we finished up our tour and found some gelato being sold at a stand in what looked like an old mansion of some sort, so we had a bit of dessert before heading back to Victoria.
So what did I think about the marble quarry tour? I was surprised by how popular and expensive it was, and how easily the visitors were distracted by the vegetation covering all the rocks. The pathways were well done, and there were lots of interpretive signs showing the glory of years past when plants didn't cover every rock, so one got a sense of history, and of loss. On the whole, it wasn't too bad, especially if you like plants and stuff like that. I don't recommend bringing a rock hammer. They got pretty upset when I starting taking rock samples.

If you want to check it out, don't go by the old name of Saanich Peninsula Quarry. They changed it, I guess when it got all overgrown. Nowadays the place is called Butchart Gardens.
The glories of the old days before plants covered everything.

A Look Back at Ten Years of Geoblogging: The Toughest Fish in the World

I've spent the last two weeks going through the archives of ten years of Geotripper. I've been enjoying picking out a few bits here and there that I really enjoyed writing. One of these was the story of the toughest fish in the world, and the very surprising place where it is found. This was posted on February 19, 2015...

What kinds of fish are tough? Some Marlin that you spent a couple of hours trying to reel in one time in Mexico? A nice two pound Rainbow Trout that fought hard against your fishing skills in a mountain lake in the Sierra? Some Small-mouth Bass in a reservoir somewhere? I doubt any of them can stack up to this little fish. They were out and about last week during our field trip in numbers I haven't seen in some time.
It's little, hardly exceeding two inches in length. It's certainly not big enough to take a hook. It doesn't have a mouthful of teeth, and it's not a predator (unless you are a diatom or a clump of algae). So how is this a tough fish?
Consider this: it lives in water that can sometimes exceed the saltiness of seawater. By three times. I don't think there is another fish in the world that can do that. can survive in water where the temperature exceeds 100 degrees. Again, I don't think there is another fish in the world that can do that. And one more: the environment in which these fish live can reaching freezing on occasion. No fish that I am aware of can survive such extremes.
But these little fish can.

On top of everything else about this species is the place where it lives, the last place one would even think of looking for fish: Death Valley in eastern California. The hottest place in the world, and the driest place in North America.

Meet the Death Valley Pupfish (Cyprinodon salinus salinus), sometimes known as the Salt Creek Pupfish. It is just one of nine or so species and subspecies of fish that survive in the Death Valley region.
Once you realize that fish are living in Death Valley, certain questions are bound to arise. How can there be water enough for them to survive? How did they get there? And how did there come to be so many species and subspecies ?
The first question is perhaps the easiest to answer. It is true that rain almost never falls in Death Valley, with an average year seeing no more than 1.5-2 inches of precipitation. But Death Valley is the lowest ground in North America, and groundwater flows towards the valley, in some cases from a hundred miles away. Springs and pools form when faults or rock barriers force the water to the surface. These water sources don't depend on the rare rainstorm. It's thought that the water flowing from springs at Furnace Creek or Scotty's Castle has been underground for more than 10,000 years. These stable springs and pools have provided a secure source of water since the end of the last ice age around 12,000 years ago.
But how did the fish get there in the first place? We can say that the fish did not arrive under current climate conditions. River connections between fault basins could only occur during the ice ages when glaciers covered about 30% of the Sierra Nevada. Glacial meltwater drained into the Owens Valley and spilled over into other desert valleys, filling them, and ultimately filling even Death Valley with a hundred mile long freshwater lake. At some point, a connection was made with the Colorado River, and numerous species of fish invaded the ecosystem. But then the ice ages ended.
The vast lakes began to dry up, and the fish were forced to adapt or die out. A number of trout species survived in the cool waters of the Carson, Walker and Truckee River drainages, but in Death Valley, it was only the Cyprinodon species. The one species was forced to survive in different environments, water that might be fresh, salty, hotter, or cooler. The single species diverged into many, much as the finches of the Galapagos Islands did.
During the spring, the Salt Creek Pupfish expand rapidly into the growing flow downstream. Hundreds of fish become thousands, then a million or more. Most of them are doomed when the extreme summer heat sets in and Salt Creek mostly dries up. A few find refuge in the pools and springs at the head of the shallow canyon (a canyon that exists on the floor of Death Valley because of faulting).

Other species of pupfish are more severely limited. The Devil's Hole Pupfish is restricted to a single cavern opening only a few tens of feet across. It is said to be the most endangered vertebrate species in America and maybe the world. There have rarely been more than 300, and at times the population has dipped to barely two dozen. Their continued survival is obviously in doubt.
Toughness doesn't have to be measured by strength or stature. The pupfish of Death Valley show their toughness by surviving in one of the most extreme environments on Earth. They deserve our respect and protection, something we have not always provided. The Tecopa Pupfish (Cyprinodon nevadensis calidae) once lived in two hot springs east of Death Valley. Modifications of the springs in the 1960s to build bath houses destroyed their habitat, and they were gone by 1970. It was the first species to be taken off the endangered species list, not because it was doing better, but because it was extinct. Let's do better with the others.

Postscript: Since I originally posted this story on the pupfish, I've become aware of another species of pupfish in the region that was thought to be extinct, but which now is thriving on private property in Shoshone, east of Death Valley. Here is the very interesting story of their discovery. Biological and environmental details can be found here.

Sunday, January 14, 2018

A Look Back at Ten Years of Geotripping: You can tell the world is an incredible place when these are the runners up...

This month I've been searching the archives for my favorite posts after ten years of geoblogging. The last two posts involved the ten most incredible places I've ever stood. What's striking is that as wonderful as these places are, I was quickly able to come up with ten (eleven, actually) more sites that weren't any less spectacular. So I posted this on May 19, 2014 as a follow-up to the list of the "best 10 places"...

I've noticed that nearly every movie reviewer puts a list of the runners up at the end of their list of the top ten movies of the year. In that spirit, I'm putting up a set of pictures from the places that almost made my top ten list of the most incredible places I've ever stood. As before, there is no particular order to these personal choices. It's a bit like asking which of your children you love the most...
 Number 20: Horseshoe Bend, Arizona
A few miles downstream of Glen Canyon Dam is a huge entrenched meander along the Colorado River. The deep blue color of the river isn't right; the silt has settled in Lake Powell, but it makes for a memorable color contrast. Learn more about Horseshoe Bend here.
Number 19: Antelope Canyon, Arizona
There are hundreds of spectacular slot canyons scattered across Utah and Arizona, and you don't have to pay to get into them, and the noontime tours can be extremely crowded, as in shoulder to shoulder, but there can be no denying that the long beams of sunlight reaching into the darkness of the labyrinth is a spectacular and unique sight. For more views, check out this link.
Number 18: Observation Point, Zion National Park, Utah
The Angel's Landing Trail in Zion is one of the most spectacular hikes in North America, but I can never forget my adventure of climbing to Observation Point on the other side of the valley and looking hundreds of feet down onto Angel's Landing (the Landing is the peak on the lower right). For more information about Zion, check out this link.
Number 17: Inspiration Point, Bryce Canyon National Park, Utah
Bryce Canyon is one of the most intricately eroded landscapes in the world, and the spires, called hoodoos, look otherworldly. Almost as incredible is to walk among the hoodoos below the rim, so here is a shot of the fir trees growing in the impossible environment of Wall Street Canyon at Bryce.
For more information about Bryce Canyon National Park, click here.

Number 16: Captain Jack's Stronghold, Lava Beds National Monument, California
The northern flanks of Medicine Lake Highland are coated in barren flows of basalt from the gigantic shield volcano. Within the flows are miles and miles of lava tubes, long caves left behind as the lava drained out. This was the setting for the Modoc Indian War of 1872-73, yet another tragic story of destroying the culture and lives of a people, in this case so settlers could have more land to graze cows and grow potatoes. It's a haunting place to stand. For more information, click here.
Number 15: The Big Sur Coast, California
A mountain range rises directly from the sea. That's about the only way to describe the incredible Big Sur Coast of Central California. This is a view of McWay Falls at Julia Pfeiffer-Burns State Park. For more details, check out this post.
Number 14: Muir Woods National Monument, California
I read somewhere that Muir Woods is the most heavily visited national monument in the United States, and I understand why. It's one of the few old growth Redwood Forests left anywhere close to the Bay Area, and it is a wondrous place to wander about. The Redwoods are ancient trees, both in individual age (thousands of years), and in ancestry (back to the age of the dinosaurs). More information about this incredible place can be found here.
Number 13: Pinnacles National Park, California
Around 23 million years ago, a volcanic center of five rhyolitic cones erupted on top of the San Andreas fault. The fault split the volcano, and the two halves are separated by 195 miles. At Pinnacles National Monument, the jointed blocks of lava and lahars have been eroded into towers and spires. The High Peaks Trail is one of my favorite hikes in North America. For more information, check out this link.
Number 12: Owens Valley and the Eastern Sierra Nevada
The most incredible wall of rock that I know is the eastern escarpment of the Sierra Nevada, a two-mile high barrier to storms and human travel. No highways cross a stretch of something close to 200 miles of mountain peaks. The Owens Valley is a deep fault trough that once was going to be one of the most important agricultural regions of California, but because of water diversions by Los Angeles, is now a sagebrush desert. Each canyon hides treasures, and I spent much of my youth exploring as many of them as possible.
Number 11: The Great Western Divide, Sequoia National Park, California
My own personal terra incognita, the Great Western Divide is a high sub-range in the middle of Sequoia National Park across the Kern River from the main Sierra Crest. It's one of the last major parts of California that I haven't set foot on, but I've looked in from the summit of Moro Rock. There are lots of places left to explore in my life...
And another Number 11 (because it's my blog and I make the rules): Mono Lake, California
Mono Lake probably belongs on another planet. It's one of the strangest sights in a state filled with strange sights, a lake that is three times as salty as seawater, with a simple ecosystem of basically algae, brine shrimp and brine flies, but the simple combination is a food source for millions upon millions of migratory birds. The edge of the lake is lined with strange tufa towers that formed along freshwater springs.

And that's my highly personal list of the second ten most incredible places I've stood, and it was just as hard to pick out as the first ten! I'd love to hear about more of your favorite places. Put them in the comments, or send me a story that I can post as a guest entry in Geotripper!