Wednesday, July 26, 2017
I suppose I should mention that we were there legally as guests of the park service, on an officially sanctioned field trip. I know that takes a bit of fun out of the story, but I suppose it's better than documenting an adventure in trespassing. We were exploring the evidence for explosive eruptive activity at the Kilauea caldera in Hawai'i Volcanoes National Park, and were walking along the edge of Keanakāko‘i Crater.
Keanakāko‘i Crater ("cave of the adzes"), probably formed in the 1400s and for centuries it was an important source of a particularly hard form of basalt that could be used to make adzes, the tools used to carve canoes and logs for walls. The adze quarry was covered by a lava flow in 1877, and a later flow in 1974 buried the quarry even deeper. It was the 1974 lava flow that we were having a look at.
The flow emanated from a rift opening just up the slope and traveled down a gully towards the main part of the Kilauea caldera. It coated the gully walls with a thin layer of pahoehoe (smooth-surfaced) basalt as it drained into the deeper crater. In other words, it was less of a lava flow than a covering layer on the gully walls. This odd occurrence revealed something interesting.
The flow must have been quite a sight as it careened down the canyon but I strongly doubt there were any witnesses, as it would have been incredibly dangerous and the radiant heat would have been deadly. Then again, someone would have put up warning signs, and any geologists would have found the signs irresistible. Maybe someone saw it after all!
Saturday, July 22, 2017
Those leading the local opposition, if they had a single brain among them, should be calling on Congress to make these monuments into national parks. I've been to Zion National Park and others in the region and they are so crowded that it is degrading the experience of visiting. It would be incredibly smart to capitalize on the demand for beautiful open spaces by making new parks to take on some of the tourism. These parks would be a marvelous addition to the crown jewels of our national heritage.
Thursday, July 20, 2017
Nearly all schoolchildren will remember that the wild horses of North America are not native to the continent, having been introduced by the Spaniards hundreds of years ago. What is less recognized is that horses are native to North America, it's just that they went extinct here at the end of the Ice Age. I've written about them before. What follows is a portion of one of my favorite posts from 2011:
The heritage of the horses is one of the greatest stories of evolution in North America. When the dinosaurs were removed from world ecosystems by events at the end the Cretaceous Period (65 million years ago), various kinds of smaller animals began to evolve to fill available environmental niches. Birds and mammals were highly competitive in terrestrial environments, and within several million years, many new species appeared in the geologic record. 52 million years ago, a small browsing animal called Hyracotherium fed on leaves in the forests. It was the size of a fox, with five toes per foot (though not all were used in locomotion). It was the earliest horse-like ancestor. Over the millenia, dozens of horse-related species evolved, with fewer toes and more highly developed hooves.
In the mid-Cenozoic, the forests were receding and vast grasslands began to develop. Some of the horses adapted to eating the grass, developing constantly growing teeth that could withstand the silica and dust without being worn away. They also grew larger and faster in order to deal with predators on the open plains. At times, a dozen or more different species of horses co-existed.
The horses were creatures of North America. Groups of them migrated into South America around 3-4 million years when the continents were joined at the isthmus of Panama. Another group migrated over the Bering Land Strait into Asia about the same time. But their home, the land of their ancestry, is North America. They thrived until around 12,000 years ago, when they and the 30 or so other species of the North American megafauna went extinct. The horses, camels, short-faced bears, giant beavers, sabertooth cats, American lions, dire wolves, and wooly mammoths all disappeared. The reasons are not known with certainty, but climate change related to the end of Pleistocene Ice Age is one possible culprit. Predation by newly arrived human beings is also suspected.
I grant that others have greater expertise than me on these matters, but the climate change idea seems problematic because there were many ice ages, more than a dozen, so why didn't these animals go extinct at an earlier time? ... Human predation makes the most sense to me, but further research will certainly be needed.
So, when Columbus and other Spanish explorers and invaders arrived in the New World with their horses in tow, they were bringing those horses back to their ancestral homeland. They did well in the wild, and over the centuries have been naturalized into the arid landscape of the Basin and Range province. Their existence is controversial, since they compete with cows and sheep for forage, and until federal legislation brought some level of protection, they were hunted and killed by ranchers. Today, they are "managed" by the Bureau of Land Management and other federal agencies, for better or worse.
I guess I'm wading into a huge controversy over the management of the horses, but I find it disturbing that there are many who only appreciate horses when they are doing work for us. Wild horses living free on the open range are to them a nuisance, as are the coyotes, wolves, and other predators that happen to eat the occasional cow or sheep. The lands the horses inhabit belong for the most part to all of us, not just the ranchers who borrow these landscapes. What I also know is that there is something beautiful about seeing these animals in the wild. There are so few creatures of the North American megafauna left, so it is a gift to see these creatures running free.
Friday, July 14, 2017
|Photo by Mrs. Geotripper|
It's big, it's active, and it's potentially destructive. So how bad could it be? Is Shasta the biggest, most recently active and most dangerous volcano in the state? Actually...no. California has a great many volcanic features, and even though some are not as familiar to many of us, they do actually present a hazard for a great many more people than you might suspect. That's not to say that Shasta is not dangerous, however.
|Castle Crags in the Klamath Mountains of northern California (photo by Mrs. Geotripper)|
Castle Crags (seen below in a picture from a plane flight a few years back) were relevant to our explorations because they represent a volcano from inside out. About 160 million years ago, the land surface was five or six miles above, and molten magma was moving up through the crust. Some of the magma reached the surface to flow in volcanic eruptions, building up volcanoes maybe similar to Shasta and others of the Cascades. The rest of the molten rock cooled slowly for tens of thousands of years, forming the crystalline granitic rock exposed today at the Crags.
Moments later, we made the imaginary journey up through the crust and onto the flanks of the modern volcanic edifice of Mt. Shasta. We followed the Everitt Highway up the mountain to the about the 7,500 foot level to have a look around. Even though we were on the first day of a crippling heat wave in California, the air was cool, and the snowbanks made it clear that winter was not yet entirely over.
There are a lot of hazards around Shasta. Lava flows might seem to be one of them, but andesite lava tends to be sluggish and slow. Lava doesn't worry me so much. Ash eruptions are certainly a danger, due to their speed and mobility. Shasta has had such eruptions, but they haven't been the usual modus operandi over the years. But...lava or ash flowing onto thick snow: that's a problem. The melting snow and debris quickly turns into a mudflow that can travel for tens of miles at high rates of speed. The Indonesians called them lahars, and the name has stuck. Most of the lower flanks of Shasta are mantled with lahar deposits, and the towns of Weed and Shasta City are built on them. Mudflows have even happened when there have been no eruptions. Meltwater can build up under the glaciers that cover much of the mountain and burst out with no warning (Icelanders call these glacial bursts jökulhlaups). All in all, it's a pretty dangerous volcano.
And it's active. There have been a number of eruptions in the last 10,000 years, including those that built up Shastina and Black Butte. The entire upper part of Shasta, the Hotlum Cone, is less than 9,000 years old. The volcano may have erupted in 1786. So is it the most recently active volcano in California? Nope.
|Lassen Peak (left) and Brokeoff Mountain (right) from Bunny Flat|
So what about the biggest? Surely a mountain 14,000 feet tall is the biggest volcano in the state of California? Well, it's certainly the tallest, and it is the most voluminous stratovolcano in the Cascades, but it actually isn't the biggest volcano in the state. When we camped that evening, we were ensconced on the flank of a massive shield volcano called Medicine Lake Highland. With the gentle slopes composed of basalt lava flows, it hardly looks like a volcano at all, but when you compare the width of the volcano in the picture below (it takes up three quarters of the skyline), you realize it is really big. It consists of around 130 cubic miles of lava, compared to about 108 for Mt. Shasta (which is the snow-capped peak on the right).
So it's the most dangerous, right?
Well...that's a hard concept to quantify. There are lots of volcanoes in California, and some are closer to population centers than others, and some are more capable of chaos and violence than others. The Clear Lake Volcanic Field, north of the Bay Area, has been active as recently as 10,000 years ago, and the Geysers Geothermal Area nearby shows that magma is still present at a relatively shallow depth. Several thousand people live in the general vicinity.
The Lassen Volcanic Center is an obvious threat, given the activity in 1914-17. There are only a few small villages in the immediate vicinity of the volcano, but it is a major tourist destination in the summer season. Lahars could presumably reach the Sacramento Valley.
The aforementioned Medicine Lake Highland is certainly still active, with eruptions as recently as 950 years ago. Although basaltic shields aren't known for violent eruptions, the presence of rhyolite plug domes around the summit area show that such eruptions are not out of the question. Like the others, the region is lightly populated.
The "elephant in the room" in terms of volcanic hazards of California has to be the Long Valley Caldera, and the nearby Inyo-Mono Craters. Every time there is a jiggle on a seismometer in Yellowstone National Park the internet lights up with predictions of death and destruction, but the conspiracy nuts pretty much totally ignore California's version of a death volcano. An eruption that took place 760,000 years ago produced 125 cubic miles of ash that covered most of the American West (the three Yellowstone eruptions ranged from 67 to 600 cubic miles). Yellowstone has not had a volcanic eruption in 70,000 years. The volcanoes in the Long Valley area of California have erupted as recently as 300 years ago. No one is talking about a repeat of the catastrophe of the 760,000 years ago, but smaller eruptions could certain cause havoc in this very popular tourist area. There was a huge brouhaha in the 1980s that had a lot of implications for how public officials respond to potential geological disasters. I wrote an extensive blog post about the event a couple of years ago; you can read it here (it's one of my favorites).
The area north of Mt. Shasta is a landscape characterized by a strange hummocky surface composed of volcanic rock, but the hummocks don't look like cinder cones or other volcanic features. Geologists didn't know what to make of this weird topography. Until Mt. St. Helens exploded on May 18th, 1980, that is. One of the most astounding events of that eruption was the collapse of the entire flank of the mountain into a debris avalanche that traveled for twelve miles down the Toutle River. It turned out that an ancient iteration of Mt. Shasta had a similar fate around 300,000 years ago, with a debris avalanche that traveled 28 miles, almost to the present location of the town of Yreka.
|The debris avalanche on the north flank of Mt. Shasta. Shasta Lake, a reservoir, is on the left within the debris field (photo by Geotripper)..|
Sunday, July 9, 2017
After traveling several thousand miles through half a dozen national parks, you'd think I would be tired of watching for wild animals, but no, that never happens. It was a nice surprise this morning to see this Red Fox (Vulpes vulpes) on my more or less daily walk along the Tuolumne River. This is the first time I've had a chance to get more than just a couple of quickly snapped pictures.
I've seen them a few times before in the area (one of my pictures of a fox is on the interpretive sign at the beginning of the trail), but it's been many months since I've spotted any. I'm pretty sure they've seen me more than I've seen them. This one was working its way across the slope where the metal stairwell climbs to the parking lot at the west end of the Tuolumne Parkway Trail. It's probably getting used to humans, as the new trail has proven popular.
There are two subspecies of Red Fox (out of around 45 worldwide!) that are native to central and northern California. One, the Sierra Nevada Red Fox, is exceedingly rare and lives only in the high country north of Yosemite National Park (it was recently sighted in Yosemite for the first time in a century). Another, the Sacramento Valley Red Fox, lives in the Great Valley north of Sacramento. This individual is neither; it is probably a descendant of foxes brought to the valley in the 1860s for hunting and fur production. The Red Foxes have adapted well to urban and agricultural development in the Great Valley (I've seen them on my mid-valley college campus), and they contribute to the control of rodent pests, but they may also be a detriment to the survival of the endangered San Joaquin Kit Fox, which has lost a vast amount of habitat and has a population of just a few thousand.
I saw a native Gray Fox in this same area several years ago. I don't know if they are co-existing, or if one has replaced the other.
Friday, July 7, 2017
I thought of Eddie when I encountered Devils Throat on Chain of Craters Road in Hawai'i Volcanoes National Park. Devils Throat is a stark example of a pit crater. There are a number of them along Chain of Craters Road (you didn't guess that one, did you?), Some of them are hundreds of feet deep. They are odd because there are no lava flows associated with their origin. They form when underground magma chambers on the rift zone of Kilauea drain, causing the land above to suddenly collapse inwards.
What he found inside was an immense inverted cone more than 200 feet across at the bottom. All the walls of the pit were overhanging. Given the fragmented nature of basaltic lava flows, such overhangs are extremely unstable. Boulders started falling essentially from the moment the pit formed. Over time, debris filled the bottom of the pit so that today it is 161 feet deep, and the opening has expanded to 164 feet. The National Park Service has never really publicized the existence of the pit over fears that people would get too close to the edge and have the rock collapse beneath them.
Mt. Shasta is a big mountain. It becomes visible from upwards of a hundred miles away. Topping out at 14,180 feet (4,322 m), it has the greatest volume of any Cascades stratovolcano at around a hundred cubic miles of lava flows and ash (the less visible shield volcanoes like Medicine Lake Highland are larger however). Driving north on Interstate 5, the mountain edifice takes on the very definition of "looming".
It's hard to get a true sense of scale sometimes when observing really big mountains, but my camera has a pretty dandy zoom lens, so I had a bit of fun with it. In the picture above, note how the center of the picture is completely snowbound, except for three rocks near the top of the ice slope. I zeroed in on it.
At the highest zoom (60x), the small dots resolve into human beings. It was a hot day in the valley, so a lot of people were up on the slopes of Mt. Shasta keeping cool. And yes, Shasta is a very big mountain.
Wednesday, July 5, 2017
I don't know much about turtles, so I snapped some pictures before they slid into the river. I immediately took to my phone to identify it, hoping it would be a native variety, but found out right away that it was an invasive species, specifically the Red-eared Slider (Trachemys scripta elegans). The only native species in this area is the Western Pond Turtle, but the red streak was distinctive to the Slider.
World's Worst Invasive Alien Species (the other is the Brown Tree Snake that decimated the native birds of Guam; I don't know how the Pythons of Florida missed the list). So my river trail is under siege. During the drought, River Hyacinth choked the river. This week I found that Star Thistle had taken root along the trail (somehow they became unrooted today; I hope for good). I don't know if anyone is acting on the turtles. They seem benign enough; they are just making their living in an environment that they can thrive in, but they also contribute to the undoing of the ecosystem.
Tuesday, July 4, 2017
|Mt. Shasta from Interstate 5 in the vicinity of Red Bluff and Corning. Photograph by Mrs. Geotripper|
I was thinking about that as we drove north on Interstate 5 in the northern Great Valley on the first day of our exploration of the Pacific Northwest and northern Rocky Mountains. We were a band of 19 students and staff on a two week journey, camping our way across some of the most spectacular landscapes on earth. Looking out the windshield I couldn't help but think that we were headed right at some particularly young and active volcanoes, such as Mt. Shasta (above).
|The Sutter Buttes north of Sacramento in the Great Valley. Photo by Mrs. Geotripper.|
The subduction zone is disappearing in geologic terms as it replaced by the growing San Andreas fault (don't panic too much, it's happening at a few inches a year). Volcanoes at the south end have been going dormant and then extinct. Once possible example is the unusual set of hills in the midst of the Great Valley north of Sacramento. The Sutter Buttes are the eroded remnants of a volcano that erupted around 1.6-1.4 million years ago. They're west of the main axis of the Cascade range, but then again so is Mt. St. Helens. Most research suggests that the volcano is more closely related to volcanic fields in the California Coast Ranges.
|Lassen Peak from the west. Photo by Mrs. Geotripper.|
|Black Butte on the flank of Mt. Shasta. Photo by Mrs. Geotripper.|
We passed one more prominent volcano before we reached the end of the road on the flanks of Mt. Shasta. Black Butte is a large looking volcano when viewed from Interstate 5 around Mt. Shasta City, but is a very small volcano compared to the adjacent edifice of Mt. Shasta (it can be considered a part of Shasta). Like Lassen, it is a plug dome that erupted about 9,800 years ago.
I'm back from a journey to the Pacific Northwest and the Northern Rocky Mountains with 18 students and volunteers. We've been gone for two weeks, and Wi-Fi was practically nonexistent, and I was constantly on the run anyway, so total internet silence ensued. I'm a bit too tired to be doing any heavy writing, so I am starting out with a bunch of photographs of the our furred, feathered and scaled friends that we met while on the road...enjoy!