Oo'-tin (Bower Cave) in the Sierra Nevada: Caverns, Lost Pictures, Dances, and the Origin Place of Humans (maybe)

The middle parts of the Sierra Nevada are kind of the great unknown of the Sierra Nevada (at least to me, but I suspect many others, too). It's not that the region between the mostly alpine national parks and the highly touristy Mother Lode is a wilderness. It's quite the opposite, with an intense history of logging, mining, dam-building, and ranching. Oh, and the elimination of the First Nations people who used to live there, so other people could build their summer cabins and the like. It's just that region one passes through while rushing to Yosemite or Lake Tahoe.

It turns out that a great many interesting places in the middle reaches of the Sierra Nevada are worthy of investigation. Deep river canyons, waterfalls, fragrant rich forests, and caverns. Hundreds of caverns!

California is not famous for its caves, but it has some world-class examples, including Lilburn Cave in Kings Canyon National Park. Lilburn has just over 20 miles of passageways, making it the 28th longest in the United States (there are more than 1,100 caves in the U.S. over a mile in length).

There is an interesting cave uphill from the Mother Lode in the vicinity of Coulterville and Greeley Hill just west of Yosemite National Park, interesting not in the sense that it's fun to explore because one cannot explore it. Well, you could, but you would have to participate in one of the most dangerous sports possible, cavern scuba diving. That's a pursuit with few margins for error. The entire cave beyond the entrance is submerged in water. It's called Bower Cave.

The interest of the cave is biological, historical, geological, and spiritual. That's a heavy load for any feature to live up to, but bear with me. The cavern opening is a large circular grotto about 100 feet (30 meters) wide, and about 35 to 62 feet deep (11-23 meters). The lake portal to the submerged caverns occupies about a quarter of the grotto floor. The overhanging walls cover about a third of the cavern floor. The cave provides a cool shelter and secure source of water during the hot dry part of the year. Animals, especially birds like swallows and owls live in the various folds of the rock. The water itself contains a few endemic arthropod species found nowhere else in the world. Fish were introduced at one time, but they didn't thrive and are gone now. Several large maple trees grow on the grotto floor. Their crowns provide the "bower" of the cave's name.

Source: http://www.karstportal.org/FileStorage/Caves_and_Karst/1969-v011-n003.pdf 

The cave was discovered early on during the Gold Rush, and when Yosemite Valley was discovered shortly after, one of the first access roads passed only a few yards from the grotto. It quickly grew popular as a cool rest stop during the long stage ride to Yosemite. John Muir paid a visit, and wrote admiringly of the cave:

Before noon we passed Bower Cave, a delightful marble palace, not dark and dripping, but filled with sunshine, which pours into it through its wide-open mouth facing the south. It has a fine, deep, clear little lake with mossy banks embowered with broad-leaved maples, all under ground, wholly unlike anything I have seen in the cave line even in Kentucky, where a large part of the State is honeycombed with caves. This curious specimen of  subterranean scenery is located on a belt of marble that is said to extend from the north end of the Range to the extreme south. Many other caves occur on the belt, but none like this, as far as I have learned, combining as it does sunny outdoor brightness and vegetation with the crystalline beauty of the underworld.

For a time a small hotel was operated nearby. The owners discovered the acoustics of the cave were excellent, so they constructed a bandstand and dance floor in the grotto. A windlass provided access at first, but a wood stairway was soon built. The party times continued into the 20th century. The property changed hands a number of times, eventually ending up in the Art Linkletter family (bonus points if you are old enough to remember him!). Someone was killed in a fall in the 1950s, so access to the cave ended over liability concerns.

Part of the bandstand still clings to the walls

A land exchange in 1991 brought the property under the administration of Stanislaus National Forest. Eventually access was restored through a permit system (one had to go to the closest forest service office for the combination to the lock on the gateway to the property). There were still worries about liability and danger from falls, so a newer gate has been constructing blocking access to the inner cave, but allowing views from the rim into the interior. Permits are no longer needed.

The cavern, as is true with most caves has developed in limestone, or more properly in this instance, marble. It is probably part of the Calaveras Complex, coral reefs and carbonate shelf deposits that were accreted to the western edge of the North American continent in late Mesozoic time (the age of the dinosaurs). Rocks within the Calaveras are late Paleozoic to early Mesozoic in age. The caverns formed when slightly acidic groundwater dissolved away the rock. The lake represents the level of groundwater in the region. In the long term, the lake will disappear as the nearby North Fork of the Merced River carves a deeper canyon and lowers the regional groundwater table. The grotto itself formed when the roof of the cave collapsed.

The cavern is unique enough that it was apparently part of the Miwok mythology. I say "apparently" because the sources date to anthropology studies in the late 1800s and early 1900s, and I haven't found any confirmation from current Miwok cultural sites on the web. I would love to hear if these stories are part of the Miwok tradition or not.

In any case, the story states that

A long time ago Too'-le the Evening Star lived at Oo'-tin [Bower Cave, on the Coulterville road to Yosemite]. He-le'-jah the Mountain Lion lived with him. They were chiefs and partners and had a room on the north side of the cave. There were other people here also To-lo'-mah the Wild Cat, Yu'-wel the Gray Fox, Kah'-kool the Raven, and many more.

The story continues with a legend of how the Raven and the early people learned to hunt deer. Some of the sources refer to the hole as a passageway by which humans entered the world. 

In any case, the cave is labeled on the AAA maps of the region, a few miles east of Greeley Hill. The trail is short, and the sights interesting. My sole visit was during the fall, and the trees were showing some nice colors.

The reference to "lost pictures" in the title of today's blog refers to the need to back up every picture file on multiple computers and external hard drives (no-brainer, right?). I took the pictures most of a decade ago, and replaced my laptop shortly afterward. I transferred all my files, but in the process, the pictures of Bower Cave disappeared somewhere. I've been through another three or four computers since then, and I've scoured the files on each of them, searching in vain for pictures I knew I had taken. That went on for years, but this week I tried one more time, and found them on a desktop that had fried her components, but I somehow managed to boot up, and there they were. And here they are. Enjoy, and if you get the chance, pay a visit to the cave on your way to Yosemite. And backup your files!

If you are interested in some of the research done at Bower Cave, check these sources:

http://www.karstportal.org/FileStorage/Caves_and_Karst/1969-v011-n003.pdf  Detailed study of the cave, part 1
http://www.karstportal.org/FileStorage/Caves_and_Karst/1969-v011-n004.pdf  Part 2, the vegetation
http://www.karstportal.org/FileStorage/Caves_and_Karst/1969-v011-n005.pdf  Part 3, the animals of the cave

What are the Most Important Geologic Roadcuts in California? A Candidate in Coulterville

In a recent post, I explored the geology of the Charlie Brown outcrop. It included excellent examples of normal faults, welded tuff, and airfall tuff, features that served as a microcosm of the geology of the entire province. I was on a field trip this weekend and saw another famous roadcut that encapsulates the geology of a different region. It was the Coulterville exposure of the Mother Lode quartz veins. It can be seen a few hundred feet west of the main junction in the village on Highway 132.

Despite extending for more than a hundred miles through the western Sierra Nevada foothills, the quartz veins of the Mother Lode are surprisingly hard to see in detail. In many places the rock has simply been removed by mining. In other instances the veins are on private property and are not accessible. But in Coulterville, the full extent of the minerals and faults of the Mother Lode are wonderfully exposed.

During the Jurassic Period, a vast subduction zone formed the margin of the western edge of the North American continent. Oceanic crust was being driven downward into the mantle, where parts of it melted to form granitic intrusions. In the Cretaceous, the focus of subduction moved west to where the Coast Ranges are today. The old subduction zone provided an avenue for mineralized solutions to rise towards the surface, where they precipitated quartz and metal deposits including gold and copper. The Melones fault was part of this system of fractures, and runs from Mariposa to Sierra City. Much of the Gold Rush gold was found in the vicinity of this fault zone. Highway 49 follows closely along the trace of the fault as well.

Mariposite at the Coulterville roadcut

The outcrop at Coulterville is the boundary between two terranes, bits of crust that were carried across the Pacific and added to the edge of the continent. The Calaveras Complex lies east of the fault, and the Foothills Terrane is found to the west. The fault zone exposes quartz veins, pyrite, and a unique mineral assemblage of quartz, ankerite, and mariposite. The ankerite is an iron-magnesium carbonate mineral similar to dolomite. The mariposite is an exceedingly rare mineral elsewhere in the world, but is found at many sites along the Melones fault. It is a chrome mica mineral formed when serpentine rock was altered by hot fluids moving up through the fault system. It was a good indicator of possible gold mineralization.

So, I'm wondering what your candidates are for the most significant geological roadcuts in California? I've reviewed the Charlie Brown outcrop, and the Big Pumice Cut that was critical to understanding the age relationships between the glacial tills and volcanic deposits in the eastern Sierra Nevada. I imagine the spectacular folded beds adjacent to the San Andreas fault along Highway 14 in Palmdale might be included. What others would you suggest?

Geological Conservancy?

Andrew Alden, as he often is, is right on top of a great idea, a proposal for a Geological Conservancy, modeled along the lines of the well-known Nature Conservancy, and less well-known groups like the Archaeology Conservancy. The proposal is outlined in some detail here, in the SIPES Quarterly. I think the idea is well worth exploring. So many geologically significant outcrops and roadcuts lie outside of national parks or monuments and are constantly threatened with destruction. Roadcuts are especially vulnerable, as road maintenance crews are often ignorant of the importance of the rock faces under their care. I've illustrated three famous sites in California that fall into this category.

The first is the Shoshone Roadcut, often referred to as the Charlie Brown Outcrop (the Charles E. Brown Highway). It illustrates in a wonderful manner the relationships of extensional faults and ash flow tuffs/air fall tuffs in the Basin and Range Province. The surrounding lands are administered by the Bureau of Land Management.

The second picture is the Sherwin Summit roadcut (the "Big Pumice Cut") that settled the question of the age of the Sherwin Glaciation of the Sierra Nevada in relation to the well-dated eruption of the Bishop Tuff. It is a cherished outcrop to legions of California geology students, but at various times road groomers have threatened to cover the outcrop with vegetation, or alter itto a great degree. I believe the land behind the outcrop is managed by the U.S. Forest Service.

The third photo is one of our local special outcrops, where quartz and mariposite veins of California's Mother Lode cross a major highway near Coulterville. The site illustrates the relationships of the ores with the surrounding metamorphic rocks which formed within a subduction zone complex in Mesozoic time. One would need access to an underground mine to have an equivalent view of these complex relationships. The land back of the highway is privately owned.

These kinds of outcrops don't have the natural constituency that places under the protection of the Nature Conservancy often have. They are not always scenic, and they generally don't form a critical habitat for rare plants or animals. But they do offer an invaluable educational experience for learning the basic principles of geology. They should have some form of protection, and a conservancy might be a good approach.

I worry a little about publicizing some of these places, though. Outside Las Vegas, at Frenchman Mountain, the UNLV geology department spent years and lots of money on building some wonderful monuments describing the Great Unconformity between Proterozoic gneisses and Cambrian sandstones. They were vandalized almost right away, and people continue to dump rubbish in the canyon (the site is periously close to a tsunami of housing developments on the northeast side of the city).

What do you think? Is this worth pursuing? How has the ability and resources to administer such a program?

What kinds of places exist in your area that deserve some kind of recognition and protection that they are not receiving now?