Monday, October 31, 2011

A Little Astronomical Surprise in Yosemite This Evening...

I'm guessing this is something you haven't seen before, but maybe I don't know how attentive astronomers are to opportunities like this. We were leaving Yosemite Valley this evening, as the sun had set and the light was fading fast. We had run out of things to take pictures of, but made one last stop as we left the valley, at the viewpoint just west of the longest tunnel on Big Oak Flat. It is the last view one has of the valley while driving west. I noticed a light shining between the sheer cliff of El Capitan and the face of Half Dome. The sky still seemed too bright to be seeing stars, but the light didn't move like a plane. I snapped a series of photos at extreme zoom (hence the not-so-great quality of the shots), and realized I was looking at the rise of  Jupiter in the east.
The zoom is at 30x, so if you click on any of the photos you can make out the disk of Jupiter.
If you think I was planning on this because of my incredible astronomical and celestial orientation skills, think again. I just got lucky. It was an interesting moment in a very interesting day.

More pictures of a beautiful fall day in Yosemite tomorrow!

Saturday, October 29, 2011

How it was Today: Fall in Yosemite Valley

Gotta get those class field trips in before the snow falls...this week it was an Earth Science class, and we headed up the hill to Yosemite Valley. The peak of the fall colors passed a few weeks back, but there were still lots of yellow and red leaves on the oak and dogwood trees tucked away in the corners of the valley floor.

The topic of the day was the geology of the valley, but this post is all about the colors of nature, and the beauty of the valley. Enjoy!

The top picture is Half Dome ( "Tis-sa-ack", or Cleft Rock in the language of the Miwok people), and an elm tree that I once called the most beautiful tree in the world.
It was a sparkling clear day. I enjoy having clouds and sunset colors to provide some variation in pictures from the Tunnel Viewpoint, but sometimes I just like having a blue sky to border the sheer cliffs.
 El Capitan is one of the most famous cliffs in the world, with a vertical drop of 3,000 feet or so.
 The clear skies lent a crispness to the leaves and needles of trees around the valley floor.
I walked across the valley floor from Yosemite Lodge to Happy Isles. I'm not sure the precise route that I took, since I kept changing direction, following the most colorful trees and sunlight.
 I was along Tenaya Creek when I snapped these two shots.
One of the campgrounds was being renovated, but that didn't keep the ravens from trying to find a way into the trash dumpsters. This one seems to be looking at me and saying "yeah, you and what army?".
There are a number of year-round springs, so it wasn't hard to find bubbling creeks, especially around the fen in Happy Isles.

The deer weren't too concerned about us curious tourists. They actually are the most dangerous creatures in Yosemite outside of us humans: they've killed more people than rattlesnakes and bears combined (not hard considering that bears and rattlesnakes haven't killed anyone in the last century).
After meeting the class at Happy Isles for a discussion of the 1996 rockfall, I hooved it back to Yosemite Lodge, and almost beat the students, who had caught a very crowded tram. Along the way I strolled through this beautiful avenue of golden colored oak trees.
It was a beautiful day, as it almost always is...

Friday, October 28, 2011

Vagabonding across the 39th Parallel: Coke, Ancient Ice, and the Tomb of the Unknown Soldier

How, asks the reader, is Geotripper going to connect those subjects into a single coherent blog post? I can't speak for "coherent", but I can do it the rest. Just bear with me!

It has a lot to do with the geological richness of Colorado. Things change quickly in the space of few miles as one wanders about the state, and wandering was what we were doing back in July. I called this off-and-on blog series about the trip "vagabonding" because we made a point of not planning our nightly stops more than a day or two in advance, and we had no particular deadlines or goals other than a desire to see Rocky Mountain National Park (which we did), and to take lots and lots of pictures.

In the last post, we had found the headwaters of the Colorado River, and were witness to the appalling destruction wrought by the bark beetles that have killed practically every tree across three million acres of Colorado. We more or less followed the Colorado River downstream, including a return to beautiful Glenwood Canyon, but when we reached Glenwood Springs, we turned south on Highway 82 towards Aspen, and then turned again onto Highway 133 traveling up the Crystal River towards McClure Pass. We stopped for lunch along the river for lunch, and I started snapping pictures of flowers (As usual, I don't know what they are. I thought lupine at first, but up close they don't look like it).
The Crystal River was running high, and quite a few kayakers were having a fine day of it on the whitewater. The weather kept threatening, but for the first time in days it didn't develop into much of a storm.
We were climbing into a high range called the Elk Mountains. They had clearly been glaciated (thus the "ancient ice" in today's title), and Ragged Mountain provided us with a fine view of the upper end of a cirque. A glacier had originated where the snow banks are today, forming steep cliffs by plucking rocks from the upper end of the valley.
The shorter peak on the right is called The Cleaver, and from another angle it provides a nice example of a small cirque and an arete, a saw-toothed ridge that formed between two parallel glaciers (the left side ridge in the picture below).
One never knows what to expect on a new road, and I had not had a chance to read up on the route we were following. Thus, we were surprised to see some odd beehive-shaped ovens along the road at the little village of Redstone. We stopped for a look and found they had been used a century ago to process locally mined coal into coke, a material used in the smelting of iron and steel (you thought I was talking about soda pop in today's title, didn't you?). They had been abandoned fifty years earlier, but local people were working to preserve them, and reconstruct four of them to their original appearance.
There was a sign a short distance up the road pointing us to Hays Creek Falls, so we had to stop there, too (I was wondering how we were going to get anywhere, but that was the point of our trip anyway). Hays was the spelling my family used until the 1920s, but I doubt there was much of a connection. There was a pleasant cascade of water spilling over a series of red sandstone ledges belonging to the Maroon formation, layers that formed in deltas and floodplains around 300 million years ago.
The road started to climb towards McClure Pass, and we had a beautiful panorama of the Elk Mountains and Whitehouse Peak. The town of Marble is tucked just out of sight in the U-shaped canyon (carved by the ice age glaciers). The town got its name from the nearby outcrops of marble that have been quarried for many years. The pure white marble is free of defects, and has been used nationwide for many purposes, including the Lincoln Memorial in Washington, and (you guessed it) the Tomb of the Unknown Soldier.
Marble is a metamorphic rock derived from the baking of limestone, which is a sedimentary rock that often forms in warm tropical marine environments. Colorado is not typically a source of high quality marble, but in this instance geological conditions converged to form the beautiful rock. The Elk Mountains originally were composed of thick layers of the Leadville Limestone that formed about 330 million years ago. Much more recently, about 20-30 million years ago, the mountains were invaded by bodies of molten magma, which baked the surrounding limestone into marble.
We reached the top of McClure Pass, and looked back down the canyon we had just negotiated. The wide meadowy area at our feet was the terminus of the glaciers, and we could see the gently sloping hills and plateaus beyond. We realized we had reached the edge of the Rocky Mountain chain. The next few days would be spent on the Colorado Plateau, a region I had been missing a lot. It had been just a bit too many years since I had last explored the region. More in the next post!

Thursday, October 27, 2011

What is it like to be the first person to step into a newly discovered cavern?

Actually, I don't know. I am not a hardcore caver who spends weekends crawling through poison oak and snake-infested outcrops looking for fist-sized openings in the limestone that might lead to undiscovered treasures beneath the surface of the earth (although I would love doing such a thing!).

But I do know that I am continually frustrated to wander through a cavern that has been overused and abused, frustrated that I can never see the various rooms in their pristine state, as they existed before human discovery. Tourist caves in the Sierra Nevada Mother Lode were mostly discovered in the middle and late 1800s. The early explorers carried smoking torches, and thought nothing of destroying delicate speleothems if it served their purposes (liking making underground dance halls and the like). Visitors regularly broke off stalactites to take home as souvenirs.

The outer reaches of California Caverns suffered this fate, as I described in my previous post.
It turns out that the miners and early visitors never noticed the debris blocking an extremely narrow passageway in the rear wall of the Bridal Chamber in the most remote section of California Cavern. A few decades ago, explorers worked their way through the claustrophobic tunnel and emerged in a large space that came to be called the Jungle Room. It was full of the most delicate cave decorations imaginable.
In the ensuing years, the passage was widened, and a trail constructed so the Jungle Room could be added to the public tour. Entering the Jungle Room is to see a pristine cave, one that is mostly untouched by the abuses that have marred many other caverns. Soda straws and helictites are two extremely delicate features that are invariably broken off by cave vandals. They are here in profusion.
Soda straws are pretty much like their namesakes, thin stalactites with hollow interiors. Some that I could see were feet, rather than inches long. Helictites are essentially soda straws or stalactites on drugs; they have forgotten that they are supposed to be influenced by gravity. They develop in random directions, probably due to water seeping out under pressure through different openings, causing precipitation of calcite in odd directions. An example can be seen coming off the stalactite in the center of the picture below.
Every corner of the Jungle Room is a revelation...I could almost feel the joy that John Muir felt when he visited the caves before they had been so badly defaced:
Here we lingered and reveled, rejoicing to find so much music in stony silence, so much splendor in darkness, so many mansions in the depths of the mountains, buildings ever in process of construction, yet never finished, developing from perfection to perfection, profusion without overabundance; every particle visible or invisible in glorious motion, marching to the music of the spheres in a region regarded as the abode of eternal stillness and death.
The cave is still active and many of the formations are dripping and streaming with water.
One of the stalagmites particularly stood out (below). Without the dirt of a century of misuse, the formations are pearly white in texture and appearance, and are simply stunning. The Jungle Room is a wonderful chance to feel, for a few moments, like you are the first person who has ever laid eyes on these treasures. It is well worth a visit.
The discovery of the Jungle Room was just the beginning. More passageways led off from the depths of the new section of cave, and the total measured length of the cavern system now exceeds a mile. The company offers extended tours of the newer passageways, but I haven't yet had the privilege (it's a bit more expensive...).

Wednesday, October 26, 2011

California has Caverns? Really? Exploring the California Underground

They are not as well-known as some other tourist attractions in the state, but California has a marvelous selection of limestone and marble caverns that are open for tours. Most of the tourist caves are privately owned, but one is in a national park (Crystal Cave in Sequoia), and another is in a state park (Mitchell Caverns in the Providence Mountains; soon to be closed due to budget cuts). There are wild caves in the Klamath Mountains, the Mojave Desert, and even a few in the Coast Ranges, but most of California's caves are found in the Mother Lode of the western Sierra Nevada and in Sequoia and Kings Canyon. There are around 1,000 known caverns, and some are world class in their features: one has more than 17 miles of passageways (Lilburn Cave in Kings Canyon).
Last weekend I returned to a cave that I haven't visited in a decade, California Caverns near the town of San Andreas in the Mother Lode. We were on geology field studies trip, and 26 students were along for the ride. I've always liked California Caverns, but scheduling considerations have usually made Black Chasm Cave our preferred choice. I looked forward to returning after a long absence. There are certain things about California Caverns that make them pretty special.

The caves were among the earliest to be discovered, in 1849 or 1850, and under the name Mammoth Cave became the first commercial cave in the state. John Muir visited in the 1890s, and found the experience inspiring:

"It was delightful to witness here the infinite deliberation of Nature, and the simplicity of her methods in the production of such mighty results, such perfect repose combined with restless enthusiastic energy. Though cold and bloodless as a landscape of polar ice, building was going on in the dark with incessant activity. The archways and ceilings were everywhere hung with down-growing crystals, like inverted groves of leafless saplings, some of them large, others delicately attenuated, each tipped with a single drop of water, like the terminal bud of a pine-tree. The only appreciable sounds were the dripping and tinkling of water falling into pools or faintly plashing on the crystal floors."

We hiked to the shed at the cave exit where we donned hardhats (for good reason it turned out), and turning around I saw a number of turkeys wandering by. I snapped a quick shot, and later on found what camouflage is. How many turkeys can you see in the picture? I count two...
After a few comments by our guide outside the cave, we entered the historic entrance, used since the original discovery of the cave by miners. No matter how many times I walk into a cave, I get a sense of anticipation, the knowledge that I about to see something new and different. And I always seem to.
With a history of 150 years of visitors, more than a few left behind evidence of their passing; one of the outer rooms has lots of historical inscriptions, otherwise known as old graffiti. I think that this is the first time I have ever seen a chandelier in a cave...

I was beginning to be disturbed by something. The cave seemed to be lacking decorations, the stalactites, stalagmites and flowstone features that one expects to be lining the walls and ceilings of the cave.
There were certainly a number of speleothems (cave decorations) in several spots; there was an ornate cave popcorn feature in one passageway. The origin of popcorn is not completely understood; it may form when the cave is still immersed in water.
A particularly beautiful cave decoration is a drapery. These form as water flows along the edge of a fin of rock. The thin formations are often translucent, and are sometimes referred to as "cave bacon".
Overall, though, the passageways seemed bereft of the stalactites and soda straws one would expect to see. In the Bishop's Palace (below), one can see a few large stalactites hanging down, but few delicate ones. It's not too hard to understand why...a century ago, it was considered OK to break off a stalactite to take home as a souvenir. I wonder how long it took before cave operators realized their visitors were destroying the very thing that made caves an interesting place to explore?
As we went deeper into the cave, I could see some delicate soda straws on the ceiling. This may have been in the Bed of Nails Room (corrections welcome if I am wrong in my cave geography). I was pleased to see these fragile features remaining from the depredations of the early cave explorers. A closer look told a different story...
Many of these inch-long soda straws were the growths of new material starting to replace those that were broken off a century ago. These small speleothems show the infinite slowness with which these features develop. Once a stalactite has been broken off, it will never be replaced in our lifetimes.
Still, a fascinating sight, and a challenge to photograph without a tripod! One thing I have learned is to take the shots on a two-second delay, so my finger doesn't shake the camera in the dim light. I try to avoid using the flash, as it washes out colors and shadows.
In the back of the historical reaches of the cave, we found the Bridal Chamber, where a massive stalagmite-slash-flowstone monument dominates the room. It is one of the cleaner, more interesting speleothems that we had yet seen, but there was still a certain sadness in my mind. The unfortunate cave has suffered a lot of abuse over the years. It certainly is not the fault of the present operators; they have worked hard to protect what is left, and have allowed many of the damaged features to start recovering (note how clean the flowstone is in the picture below). But the damage is still there, from decades of ignorance and even vandalism.

We had reached the back of the cave, at least as far into the cave as the miners and early tourists ever explored. Something special that was about to happen...which we will talk about in the next post!
California Cavern is operated by the Sierra Nevada Recreation Corporation. Information about tours can be found here.

Tuesday, October 25, 2011

Depth Matters: A Tour of the Kennedy Mine Property in California's Mother Lode

We took one of our fall semester field studies trips last Saturday, to the California Mother Lode between Jackson and Columbia. It included a tour of a spectacular marble cavern (in a coming post), and the Kennedy Mine, which for a long time was one of the most important gold mines in the state.

The mine was the subject of my last post, a first impression of some of the info I learned during the tour: how people died working underground. The tour at the mine was conducted by volunteers working with the Kennedy Mine Foundation, a non-profit organization, and our guide was a fountain of information. The tour is above ground, as the mine was vertical for hundreds of feet, and flooded to boot. Our tour actually lasted 40 minutes longer than the scheduled 90 minutes, which caused me a bit of stress as I was watching the clock ticking towards the appointment time for our other scheduled tour! It was a great opportunity to see one of the most important mines of the Mother Lode.

The grounds are heavily overgrown with gray pine and oak trees, and the site is actually preserved as open space for wildlife (the wishes of the last owner of the land). This was quite a contrast to the old days; a look at old photographs indicated that the site was actually pretty barren of vegetation during the mining years.
The headframe will last a long time. It is 135 feet tall, and composed of iron beams. The original 100 foot tall wooden headframe burned (along with most of the surface developments) in 1928. Debris from the burning headframe fell down the main shaft, blocking any chance of exit for the miners still working thousands of feet below. A previous tragedy saved the men's lives: in 1922 the adjacent Argonaut Mine had burned and 47 miners died. In the aftermath, a connecting tunnel was left in place at the 4,600 foot depth between the two mines. This tunnel allowed the miners to escape unharmed.
The building in the picture at the top of this was the changing room, where miners coming off their shift could shower and change cloths before going home. It serves today as a museum and gift shop. The showers weren't really a job allowed the mine operators to make sure no one was walking home with gold samples in their pockets! The practice, called high grading, was a constant problem for the mining companies (maybe if they paid their workers better?).
The cement monoliths above are the foundations of the main hoists for the mines. Keeping air in the mine breathable required an extensive ventilation system; carbon dioxide is a heavier gas and could often sink to the lower reaches of the mines and cause suffocation. If you remember the phrase "canary in a coal mine", it reflected a truth. Miners would carry canaries, which were more sensitive to bad air than humans. If they stopped singing, miners knew they were in danger.
Ore was hoisted to the surface of the mine, and processed in a stamp mill on the slope below the headframe. The Kennedy Mine had one of the largest stamp mills in the entire Mother Lode, with 100 stamps. Each stamp weighed nearly half a ton, and they were in constant motion, vertical hammers rising and falling, crushing the ore into a sand-like consistency. Mercury and other "benign" chemicals were used to separate the gold from the waste material. Mercury combines with gold to form a solid alloy called amalgam.

The mine waste was a problem. It was full of sulfide minerals that converted to acids on exposure to the atmosphere, and water in the town below was being fouled. In the early 1900s, a system of buckets and giant wheels was constructed to carry tailings over a nearby ridge to a reservoir that could isolate the poisons from the domestic water supply (you can see pictures of the wheels here).
 The monstrous piece of metal in the picture below was a camshaft that was used to lift the stamps.
The mine office is the best preserved building on the mine property. It was built in 1908, and was one of the only buildings to survive the 1928 fire. It included some contradictory operations, although they make a certain amount of sense when one thinks about it. There were two big blast furnaces, one for separating the gold from the mercury, and the second for melting the gold and producing ingots for delivery to the mint in San Francisco. I have to imagine that the whole building must have been terribly hot in summertime (temps in the Mother Lode often exceed 100 degrees). The other side of the ground floor was the assay office, which tested ores at the end of every day, so the quality of ore was always known.
The second floor contained mine offices, the safe, and the pay room. Miners made around $4 a day in the 1920s, and specialists (foremen, carpenter, assayers, and blacksmiths made almost twice as much). These were fairly reasonable wages for the time.
The third floor contained four bedrooms of all things. They were there to house investors when they paid a visit to the mine. They mostly lived in San Francisco and the journey could be long and dusty.
The view from the mine office building is quite nice, overlooking the town of Jackson, and the eroded volcanic neck of Jackson Butte, seen in the picture above.

The Kennedy Mine operated unsuccessfully from 1860 to the late 1870s. New technology (especially the invention of dynamite and steam operated drills) led to a successful expansion of the mine in the 1880s, and the Kennedy operated profitably until 1942 when it is shut down by presidential decree during World War II. When it closed down it was the deepest mine in the United States at 5,912 feet. It ultimately produced about 1.5 million ounces of gold, worth about $2.4 billion at today's prices. It was one of the biggest gold producers in the Mother Lode.