Saturday, November 28, 2015

The End of Fifty Miles of Sand: The Oregon Dunes

Or maybe, more properly, the beginning of fifty miles of sand. It's generally moving south from this point. The west coast of North America is mostly mountainous, with dramatic cliffs sloping almost directly into the sea. Where the east and south coasts of the United States might have strands of sand that run for hundreds of miles, sand is rare enough in the west to be a curiosity. If fifty miles of sand is found in one place, it is extraordinary. That's where I spent my Thanksgiving, next to Oregon Dunes National Recreation Area.
I've always made a point of resisting the orders of our superiors to go out and buy things the day after Thanksgiving, being a firm supporter of the the idea to "leave no child (or anyone else) inside" as a form of personal education. We went exploring the coastal area around Florence this weekend.
As I've noted in previous blogs, the so-called Coos Bay dune sheet extends for 56 miles (90 kms) from Coos Bay to Florence, and it is a strange and bizarre landscape that contains 85% of Oregon's active dunes. It's mostly protected as Oregon Dunes National Recreational Area. It isn't that there is simply a long expanse of sandy beach; the sand has been blowing and migrating inland, in some places nearly 3 miles, covering forests in some cases, and in other situations, stabilizing and becoming forest. This odd environment makes for unique ecosystem and geological landscape, mixing ocean, swamps, rivers, forests, and lakes.
You can get a hint of the transition of dune to forest in the pictures here. I was quite literally standing above the very last dunes of the system, about eight miles north of Florence, where cliffs once again dominate the shoreline. The irregular hills are sand dunes that have been stabilized with European Beachgrass to augment the stabilization of migrating dunes. The native grasses have been pushed aside in many instances as the European non-native takes over. Because of the spread of grasses, 80 % of the dune sheet is covered by vegetation. In 1939 it was only 20% (US Forest Service data).
Only a few hundred yards inland, conifers have started to take root.  The rivers and streams that flow into the dune fields, along with a high groundwater table, have created a network of swamps, and more than two dozen ponds and lakes (before I began exploring this region I would have said that lakes form only from glaciers, sinkholes, landslides, or oxbows on floodplains; dune lakes were new to me). The complex provides a rich environment for wildlife.
The sand has several origins. The quartz rich sands have been eroded from distant sources in the Klamath Mountains and Idaho Batholith and carried to the shoreline environment by one of Oregon's many rivers. Other sand is locally derived, eroded directly from the sea cliffs, or carried onshore from offshore bars, sediment that may have originated during the ice ages when sea level was lower. Wave action produced the flat platforms on which the dunes accumulated.

It's a beautiful and dramatic landscape. If you ever get the chance...well, make the kind of choices that will get you chance to explore places like this!

Wednesday, November 25, 2015

Wishes for a Happy Thanksgiving, and Safety for Those on the Road

Here's hoping that you all have a fine Thanksgiving holiday and that your travels are safe and fun. I offer up one of the things that I am truly thankful for: politicians that put aside their many differences and agreed to establish Pinnacles National Park in 2013. Maybe we can all learn something from the shock of actually working together and compromising: Democrats, at dinner this week be kind to your Republican relatives, and Republican relatives, be kind back. Be thankful that we can still argue politics without fear of reprisals.

Pinnacles National Park has provided us with our picture of a turkey for this Thanksgiving season. I doubt this one will be gracing anyone's table, as he was well inside the boundaries of the park. Maybe a coyote's, but this one looked like it wasn't going to take any crap from anyone.

Pinnacles has been one of my most dependable localities for seeing Wild Turkeys (which are not exactly a native species, but they have become naturalized in this region). I've seen dozens at a time there. The turkeys can be seen throughout the Coast Ranges. It's not well-known, but the Wild Turkey was almost hunted to oblivion a century ago. Aggressive efforts at conservation and introduction of captured wild birds to new regions (including California) brought them back.

A few years back, I caught a bit of a conflict, a love triangle if you will, in Morro Bay.

Pinnacles National Park is a beautiful place with fascinating geology. Look for a couple of posts soon from our recent trip there.

Short story of the geology: it's half of a large composite rhyolitic volcano that has been deeply eroded. Where the other half is today is part of the exciting story. The rest is the idea that you can wander around in the middle of volcano in the Central California Coast Ranges.

Pinnacles is a treasure. If you ever have a chance to explore central California, be sure to add it to your itinerary! In the meantime, have a safe and happy time wherever you may be. I'll be on the road, so posts may be scarce.

Getting a Creepy Feeling in Central California: A "Transforming" Experience

Faults can be active without producing major earthquakes. When the fault plane is not locked by frictional resistance, the sides of the fault can slide past each other without building up the stress that leads up to huge quakes. In Central California, there are several faults creeping on a more or less consistent basis year after year. They are close enough to each other that they can be easily visited in an afternoon. That is exactly what we were doing last Saturday.

The town of Hollister is bisected by the Calaveras fault, and numerous homes, sidewalks, and streets are slowly being torn apart by the constant movement, amounting to as much as 14 mm/year (0.55 inches). The embankment in the photo above appears in a number of geology textbooks as an example of fault motion.
The foundation for this 1920s vintage garage has also been seriously damaged. We've been visiting the spot for 28 years. It will be disappointing when they finally decide to renovate the building!
Probably the most famous example of fault creep in the region can be found at the DeRose Winery a few miles south of Hollister. The fault is far more active, with yearly offsets amounting to as much as 25 mm/year (1.0 inches). One can get a sense of the magnitude of the motion by comparing Saturday's image to one taken half a century ago (below) 
Source: NOAA/NGDC, University of California, Berkeley.
The DeRose Winery has changed hands a number of times in the last 160 years, and the owners of the place in the 1980s kind of let it go (I believe they were even trying to produce tiger prawns in the old wine vats for time). The current owners are a treasure. They recognize the scientific value of their property, and have been clearing weeds from the drainage that threatened to completely hide the iconic symbol of right lateral strike-slip motion. They have also never refused us entry into the warehouse where offsets accumulating since 1948 are nicely exposed in the walls, even when formal wine-tasting has been going on.

All of these incredible exposures are easily accessed. If you are ever in the vicinity of Hollister or Pinnacles National Park, don't miss the opportunity to lay your hands on a major transform plate boundary!

Sunday, November 22, 2015

You Say it's Winter Already? Fall Has Just Arrived in California!

Some people say they could never live in California. The earthquakes are scary and the state will fall into the sea. The politics are too crazy. It's an urban hell. Californians are too flaky. Pick your reason. But there are things that are undeniably nice about California. Our fall season is one of them.
Oh, it's true that my fair state can hardly compete with the extravaganza of New England's colorfest, but that color show was over a month or more ago, and people are complaining about the arrival of winter. Meanwhile, here it is almost December, and our fall season is just getting going. And while some folks will still be shoveling snow in April, we'll be enjoying the blossoming of our almond and peach trees in late February.
The first two pictures were snapped yesterday at Pinnacles National Park, but we have a lot of color in our supposed "worst place to live" cities too. The picture above is just a few blocks from my college. The peach orchard below is across the street from a major shopping center. In a few months there will be a blizzard of beautiful pink blossoms.
Of course, with the coming of fall, it's getting COLD. I almost thought of putting on jacket one morning the other day but decided in the end to tough it out in a t-shirt. It only got to 70 degrees outside today. I just don't know how much longer I can stand the suffering!

Anyway, enjoy the late season colors. We'll probably have an earthquake because I was being a little snarky.

Saturday, November 21, 2015

Why did the Road Cross the San Andreas Fault? 13 Years of Geologic Change (an Update)

I've been leading geology field studies trips to lots of places in the American West for 27 years and started to take digital pictures in 2001. I sometimes struggle to find new things to photograph when I visit a place for the 27th time, but in some cases it is not a problem. There are geologic changes that happen on a yearly basis, and with thirteen years of photos, the changes become obvious. This is an update from a post in 2013, and I'll probably continue updating for the foreseeable future.
Highway 25 in the California Coast Ranges connects the town of Hollister with the access road to Pinnacles National Park (formerly Pinnacles National Monument). Along the way the highway crosses the San Andreas fault in a section where the fault creeps an inch or so each year. Most years we've stopped to have a look at the effect the movement has on the pavement. In 2002 and 2004, the damage was obvious.
By 2008 someone had patched the road, and no fault motion was evident.
Little damage was evident in 2009 either. But by 2010 cracks had begun to appear as the fault stressed the pavement.
The fact that the fault creeps in this region is a good thing. It means that stress is not building along the fault surface, but instead is being released gradually. The sections of the fault to the north and south of the creeping section are locked by friction, and are building up the ominous stress that will eventually produce quakes with magnitudes in the range of 7.5 to 8.0. The quakes are coming and we need to be as prepared as possible.
By 2012, the road had been completely repaved, and  yet the shearing was already evident.
It became even more pronounced by 2013 and in 2014. Just by chance, the person working as a scale was the same individual as in 2004. I've got some great people who volunteer and make these trips possible

Today we stopped at the fault crossing again. The fractures are moderately larger. They'll need to start thinking of road repairs before long.
These little changes that happen at a rate visible in human lifetimes add up to huge changes when multiplied by thousands or millions of years. The nearby eroded volcano of Pinnacles National Park has been displaced 195 miles (315 kilometers) in the last 20 million years or so by movement along the San Andreas.
Until next year!

Friday, November 20, 2015

A Small City Recognizes Her Greatest Treasure: Tuolumne River Parkway Trail Nears Completion (update)

I've been providing occasional updates on the progress of the Tuolumne River Parkway trail that is being constructed in Waterford, California, where the river leaves the Sierra Nevada behind and flows into the Great Valley. It's been a source of some community pride that the city has finally come to realize the value of the river. It used to be a dumping ground. Now it will become a learning resource for our children, since the trail will be within walking distance of three different schools.

Progress seems to alternate between "none" and "very rapid". There were several weeks where nothing much would seem to happen, and then practically overnight a section of trail will suddenly sprout fully completed slope barriers. The barren field at the top of the bluff was ignored for weeks, and seven days ago, a paved parking lot appeared. Today was one of the rapid days. A stairwell will be necessary to provide access from the high bluffs on the downstream end of the trail. The foundations for the stairwell have been in place for a month or more, but nothing more seemed to be happening.
As I walked down the trail, I could see a huge crane in the distance (and it wasn't of the Sandhill variety; sorry for the bird humor). Workers were lowering a section of the stairwell into place. More than half of the stair sections had already been put into position.

I watched for a few minutes as the foreman directed the crane operator by walkie-talkie. It was interesting because the operator was completely out of sight above the bluff, but he or she had such a delicate touch that the stairwell section was lifted or dropped six inches at a time to get it into the right spot, based only on the verbal directions from the foreman below.

My walk today once again illustrated the value of this stretch of the Tuolumne River. The thin artery of water and the related riparian habitat is a sanctuary for dozens of bird species and other creatures. I've seen all manner of small rodents and reptiles, and the occasional Gray Fox. On this particular day I was able to capture some photos of birds that I rarely see in urban settings.

I've seen them elsewhere (at the San Joaquin NWR, Pecos National Historical Park, and my west campus), but this was the first time I've seen a Say's Phoebe along the river trail.

Acorn Woodpeckers (above) are common along the river, and I always enjoy watching their antics. They look like clowns, and sometimes act like them. They are endemic to the southwest, Mexico and Central America.

I've yet to see a Black-chinned Hummingbird in my yard or the local pasture, but I've seen them numerous times along the river, both in August and today, in mid-November.
It's not Yosemite National Park, and it's not one of the Serengeti-like bird refuges with tens of thousands of migratory geese and cranes, but it is a small bit of river that preserves a natural environment with species numbering in the hundreds. I see something new almost every time I walk this trail that is almost literally in my own backyard. It's our city's most precious resource. I look forward to the completion of the trail in a few weeks.

Wednesday, November 18, 2015

The Karst Topography...of California? There are more than 1,000 wild caves in California. Here's one of them

There is something special about exploring a wild cave, the kind without admission fees, guides, trails, and railings. There are a thousand limestone caves in California (and hundreds of lava tubes), and not even a dozen of them are show caves, i.e. open for business.There are usually reasons the wild caves do not become "tour caves". They may be too short, too inaccessible, maybe even too dangerous.
The wild caves have suffered varying levels of abuse and vandalism. Few of them are protected by any kind of legal authority and are rarely patrolled. They are mostly protected by secrecy, and small groups of serious spelunkers. I've been privileged with the opportunity to explore a couple of them, and as part of my miniseries on the karst terrain of California, I'd like to share one with you.
A nearly empty New Melones Reservoir and the gray marble of the Calaveras Complex.
Karst topography, as described in the previous posts, is a landscape underlain by cavern-filled marble or limestone. Cavern roofs can collapse, forming sinkholes, blind valleys and disappearing streams. The marble, a part of a metamorphic terrane called the Calaveras Complex (late Paleozoic-early Mesozoic), can be seen as gray slopes in the photo above. Many incredible caves were drowned by the waters of the reservoir in the foreground of the picture. Others open out into sheer cliffs above. Few are easily accessible. We had to walk a steep mile to get to the caves we're exploring in the post today.
Oak woodland in the vicinity of the caves
That's what makes these caves special. They are at the end of a pretty stiff hike, but they have accessibility, and are relatively undamaged (this concept is relative; some would call them heavily damaged, but many parts are in good shape). They're not crowded. Months may pass between visits.

When we have a group of newbies who have not explored wild caves before, we do some training on safety, both for the explorers, and for the caves themselves. We stress the importance of exploring in least intrusive way possible, not touching the rocks, and not disturbing any life if possible. We crawl through a short cave with a few narrow passages in preparation for entering the much larger cave to follow.
We finish our spelunking practice at the small cave, and move on towards the larger, more challenging cave. Accessing the cave requires first descending between huge fallen boulders. The cave had grown so large that portions of the roof had collapsed to form a sinkhole. We find a spot with good footholds and climb into the darkness.
The second challenge is getting into the main cave via a narrow passageway at the base of the rockfall. One has to push upwards and twist through the tight little space. Some of the explorers describe it as being "born again".
The entrance merges into a more open room that serves as the "subway" into the largest room in the cave. This passage is where most of the speleothem damage has occurred. It's not exactly the work of vandals, as the breaking of the formations was probably for the purpose of making an easier passageway into the room beyond. This kind of thing happened to many caves discovered in olden days. I don't know anything of the discovery and original exploration of this particular cave.
This passage leads into the main room of the cave, which more than 100 feet long, and 20-30 feet high in places. We come face to face with a spectacular wall of mostly unbroken stalactites (they were protected by being out of reach).
The room is richly decorated with all kinds of dripstone and flowstone features. Some are brown from torches of the early explorers, or from mud seeping through the cracks above. Other features show evidence of recovery from the "dirty early years". The adoption of clean caving techniques in the last few decades shows as some of the cave features are covered with a thin layer of pure white calcite. Some of the caves are being cleaned by volunteers as well. In some cases, people haul gallons of water down difficult trails, set up hoses into the caves, and then spray mud off of damaged speleothems.
There are all kinds of nooks and crannies to explore. There is a false floor in the cave that offers a loop crawl. There is a small passageway called the bedroom and another called the jail room. Openings high on the walls and ceiling hint at other passageways. In a side room, one can view a sinkhole from the underside, looking up at a mass of boulders that had collapsed down into the cave, but have since been cemented together by flowstone to form the ceiling of the room.
What about cave life? We've seen spiders near the entrance, and unusual looking snails. In previous trips we have seen six inch long centipedes, and Ensatina salamanders. There have been a couple of bats. The total darkness of caverns offers little in the way of food, so the biomass quantity of the cave is very low. The creatures that do exist are highly adapted to environment of the caves.

The wilderness caverns of the Sierra Nevada are a precious and irreplaceable resource. The breaking of any speleothem destroys the result of thousands, even tens of thousands of years of slow development. They can never be replaced in any kind of human lifetime.
It is a rare privilege to be able to explore this underground wilderness, and it is a privilege for me to introduce my students to this strange new world.
A cave is such a strange and alien world for a human being, at least the deeper parts away from the light. No wonder that some of our first art was scrawled on cavern walls as sort of drug-free hallucination of alternate worlds. Caves were portals to lower worlds, or were the avenues for emergence into our current world. Sitting in the darkness, I can feel a connection to my ancestors.

You have no doubt noted that I have not provided the names of the caves we explored. If you want to get involved in cave exploration, you should contact your local grotto of the National Speleological Society. They provide instruction and training, as well as chances to clean and rehabilitate caves that have been damaged by vandals and overuse. They are great people. And don't forget, the tourist caves in the Mother Lode are wonderful. They are safe and easy to explore. Check them out!

This post is a highly altered version of a post based on our trip in 2014. If you want to see how badly I plagiarized myself, check out the original post here: