A Bit of Drama on the Tuolumne River...

Every visit to the wilds holds the possibility of the unexpected surprise. There is the "usual" sense of discovery when one finds a new bird species, or some otters playing in the water, and then there is the just plain weird. I don't see snakes very often, as there are a fair number of people on the trail and the snakes wisely stay out of sight. In fact, the only snake I'd ever seen before today was dead.

But today was something. I was on a low bluff over the river gravels, and I happened to look down to see what looked like a huge snake (of course every snake looks really big at first). I realized it was a California Kingsnake (corrections welcome), and it was big, maybe three feet, but not huge. I got the camera out and got a few shots before it disappeared into the brush.

But then the weird part: it was being followed by a California Quail. I couldn't tell if it was chasing or harassing the snake or carefully monitoring the snake. I have to think that in some way it had to do with the defense of a nest, but I have no real basis for the speculation. Maybe it was just curious...

Tales from the Semi-Super-Bloom Tour, Part 4: Into the Realm of Demons, the Red Hills

Human mythology finds bigger meanings in everyday stories, i.e. vast battles fought in the heavens, on earth, and in the depths below pitting light against darkness, fire against ice, and good against evil. In many ways, the myths reflect the seasons, with the richness of spring and summer contrasted with the dying and death of fall and winter. That's what I was thinking about when we made a trip this week up to the Red Hills Area of Critical Environmental Concern in the Sierra Nevada foothills. The trip was another stage in our Semi-Super-Bloom Tour, our effort to visit some of the less heralded places in California where the "Super-Bloom" was not quite as spectacular (and therefore less crowded).

We had been here some weeks back, but the spring wildflowers were only just beginning to show up. And when we arrived this week, most of the flowers were already dying back and going to seed. But there was still color hanging on here and there, especially where water was still providing the gift of continued life. It reminded me of mythical legends of latter ages when the glories of the past were still remembered, but the power and majesty of said civilizations was waning, and facing climactic battles against the forces of darkness that threatened to overwhelm all.

Really...wilting flowers make me think that way...

I imagine that it is really stretching metaphors and symbolism, but these fragile flowers are truly facing a horrific test of their ability to survive. The Red Hills take their name from the serpentine soils that weather reddish brown. The soils are poor in necessary nutrients, and rich in metals and other chemicals that are toxic to most plants. Even the name of the host rock, serpentinite, recalls ghastly mythical animals like giant snakes and dragons.

And there is an additional curse: the climate. Rain falls only in the winter and spring (most years anyway), and when the rainstorms stop, they stop entirely, for six months or more. The land bakes in 90-100 degree temperatures throughout the summer and into the fall. Life struggles to exist in this harsh environment.

And yet life does persist. The flowers rush to maturity, doing everything they can to reach maturity and produce seeds before the dryness takes life away once again. And during those short weeks, the slopes are wild with beautifully colored wildflowers. The darkness and fire for a brief moment are forgotten.

The rocks themselves that make up the bedrock of the Red Hills are truly from the realms of demons and devils. The serpentine and other ultramafic (extremely rich in iron and magnesium) rocks originated deep in the underworld that exists beneath the Earth's crust, at depths of 20 miles or more (a layer called the mantle). The rocks were carried towards the surface along huge fault systems and subjected to the reactions of extremely hot chemical-rich water and intense pressure. The rocks have been sheared and twisted to the point of being unrecognizable. Although the rocks rarely contained gold, they are closely associated with the gold-bearing ores found nearby.

The Red Hills were once reviled as was befitting of an infertile barren landscape, a landscape blasted by heat and drought. Off-road vehicle trails scarred the landscape, and some locals used the area as a dumping ground or as a shooting gallery. The land was owned, but ignored, by an agency of the federal government, the Bureau of Land Management. The BLM grew out of the efforts to give lands away under the auspices of the Homestead Act in the late 1800s. The problem was that no one wanted the lands held in many areas, so the BLM eventually became the custodian of something like 250 million acres, mostly across the western United States.

As attitudes evolved regarding land-use and ecosystems, many BLM-managed lands came to be appreciated for their biological and geological values. More and more of these "abandoned" lands were transformed into more than 200 wilderness areas and nearly 30 became national monuments. The Red Hills properties were not roadless enough to be considered as wilderness, and neither the president nor Congress ever considered it for national monument status (although I don't think it would be a bad idea). Instead, when local communities began to advocate for protection of the Red Hills for their scientific and recreational values, the BLM responded by designating 7,000 or so acres as the Red Hills Area of Critical Environmental Concern. Despite the clumsy title, the designation protects the hills from off-road vehicle use, dumping, and shooting. And during the late winter and spring, tens of thousands of people will visit the site. There are minimal developments, a pit toilet, a parking area, and a series of roads and trails that provide access to much of the "park".

The explosion of vegetation in the spring attracts insects and animals. During our trip, we saw a number of birds, including California Quail and Bullock's Orioles. They added an additional splash of color to this fascinating landscape. It was an interesting day in the realm of the devils and demons of the underworld.

Driving Across the Most Dangerous Plate Boundary in the World: These Rocks are All Wrong!

The view from Muir Beach Overlook, midway between San Francisco and Point Reyes National Seashore

Point Reyes National Seashore: Is it land's end, or ocean's end? From a human point of view, it is the former. This is the far west of North America, and you can't go any farther without a boat or plane. But if we consider the oceanic crust that was being subducted beneath the continent here, it is the latter. It's where the ocean floor came to an end by being consumed and presumably melted within the Earth's mantle, the subcrustal layer that extends to the core some 1,800 miles down. In any case, it is the starting of our journey across the most dangerous plate boundary in the world. As I've pointed out before, it isn't presently the most dangerous boundary; it changed long ago, and the stripping effect of erosion has revealed the inner workings of the subduction zone that produced much of California's present-day landscape.

Drake's Beach, with outcrops of Purisima Formation that reminded early sailors of Dover.

But the rocks at Point Reyes are all wrong! As was mentioned in the first post of this series, an ocean-continent convergent boundary (a subduction zone) consists of three structural features: an accretionary wedge, a forearc basin, and a magmatic arc. The wedge deposits should be found nearest the coastline, and the granitic or volcanic rocks of the magmatic arc would be found far inland. As we look around at our journey's starting point at the lighthouse at Point Reyes, we find rocks related more to the magmatic arc. There are exposures on the Point Reyes peninsula of granitic rock, metamorphic rocks, and the silica rich sediments that have been eroded from them. Why are things out of order here?

It's due to the structural changes that resulted in the cessation of subduction and the beginning of movement on the San Andreas fault. At transform boundaries like the San Andreas, the crust and upper mantle (the lithosphere) are shifting laterally. The rocks west of the fault, Point Reyes, the Central Coast's Salinian Block, Los Angeles, San Diego and the Baja Peninsula are moving as a unit to the northwest, more or less towards Alaska.

Around 30 million years ago the rocks of Point Reyes were in Southern California. Around 29 million years ago a major restructuring of plate boundaries took place. Granites and metamorphic rocks related to the Sierra Nevada were sliced off and started their northward journey and we find them today underlying the lighthouse at Point Reyes. And that's where we now start our journey across the most dangerous plate boundary.

Source: USGS (http://pubs.usgs.gov/of/2005/1127/)

I'm afraid we've got a bit of a walk before we can get in a car and start driving. The lighthouse at Point Reyes is situated midway up the cliff above the sea, and we've got a climb of about 300 steps to reach our road. The rocky headland where the lighthouse is located is composed of granitic rock and some overlying late Cenozoic sedimentary rocks.The rocks are resistant to erosion and stand as a high rocky point.

Photo by Mrs. Geotripper

Take a few deep breaths and start climbing...

The cliffs of granitic rock are steep and nearly vertical. If you listen carefully, you may hear the barking of sea lions in the small coves below. During the right time time of year you may spot some of the migrating whales offshore.

The climb, though, is worth the effort, because when we reach the top of the hill there is a marvelous view to the north towards one of the longest unbroken sandy beaches in central or northern California. One might think it would be a popular swimming beach, but the fierce winds, high and unpredictable waves, and cold water make for uncomfortable conditions.
From this lofty perch we can make out the mountainous terrain of Inverness Ridge, composed mostly of the granite and metamorphic rocks of the Salinian Block. The gentle westward slopes expose sedimentary rocks of Miocene and Pliocene age, deposited during the long journey northwest from Southern California when the rocky basement was submerged beneath the ocean waves. Active dune fields can be found along the extensive beaches of the peninsula.

The peninsula is protected from development as Point Reyes National Seashore, and is a haven for wildlife. On our drive towards the "mainland" we are likely to see numerous bird species, including California Quail. A herd of Tule Elk graze the grasslands along the road.

The road climbs over the crest of Inverness Ridge and descends to the village of Inverness and the shores of Tomales Bay. We've reached the San Andreas fault, the second most dangerous plate boundary in our narrative. Maybe the rocks will be "right" when we find a way to cross the boundary between the Pacific and North American plates.

Civilization Exists By Geological Consent...So does life in the Great Valley

Sandhill Cranes at the San Luis NWR

The Sandhill Cranes are returning to their winter home in the Great Valley of California! In the next few weeks there will be 20,000 of them arriving at the Merced National Wildlife Refuge a few tens of miles south of Modesto. They will be sharing space with hundreds of thousands of other birds, including Snow Geese, Cackling Geese, Ross' Geese and many others. To many pundits, the Great Valley of California is a rotten place to live (see my comments about this from yesterday's post). But if you are a bird, the valley is next to paradise. It represents survival, and the reasons are geological.

Sandhill Cranes at the San Luis NWR

The Great Valley is 400 miles long, and around 30-40 miles wide, running from Redding at the north end to Bakersfield in the south. It is amazingly flat, with total relief of only a few hundred feet. Two major river systems, the Sacramento and San Joaquin, provide a richness of water in what would otherwise be desert or near-desert. A huge range of habitats existed here at one time, including short-grass prairies, riparian floodplains, oak woodlands, lakes, and vernal pools. Although agriculture and urban development have co-opted some 95% of the valley floor, there are still pockets of native environments remaining.

Killdeer at the Merced NWR

The valley originated as a large shallow sea called a forearc basin along the vast subduction zone that once existed across the entire west coast of North America. The convergent boundary was eventually changed, and the San Andreas transform took its place. The Coast Ranges rose in the last few million years, acting as a rain shadow, and preventing the rivers from finding an easy path to the sea. The Sacramento and San Joaquin rivers flow outward through the Carquinez Strait, but several other rivers, including the Kings, Tulare, and Kern, don't reach the sea. Prior to settlement and diversion of the rivers for agriculture, they ended in large shallow lakes at the south end of the San Joaquin Valley. The lakes are dry today.

Yellowlegs (Greater?) at the San Luis NWR

Though so much of the original valley habitat is gone, a few critical wetlands remain and are preserved as a string of National Wildlife Refuges. These refuges are a critical component of the migratory flyway for millions of birds. Some simply pass through, stopping long enough to eat and gather energy for their long journey, but others spend the winter here, and some stay all year.

California Quail at the San Luis NWR

Many tourists pass through the Great Valley without a second thought on their way to Lake Tahoe, Yosemite, or Sequoia/Kings Canyon, but at this time of year they are missing an awesome show of the variety and diversity of nature. There is nothing quite like seeing and hearing the spectacle of 10,000 geese taking off all at once. There are hundreds upon hundreds of bird species who spend at least part of the year in the valley, not to mention a rich variety of mammals, reptiles, fish and amphibians. The valley for all its problems can be a fascinating place to spend some time.

Great Blue Heron at San Luis NWR

The San Luis National Wildlife Refuge Complex includes 45,000 acres of protected lands within an hour's drive of Modesto, my home base. There are a number of hiking trails (all level, imagine that!) and several auto tours, including those at the San Luis and Merced Units where I took all of these pictures today. I think we saw or heard at least three dozen species of birds in just the four hours we spent exploring.

Northern Shovelnose at the Merced NWR

We were entranced by the hundreds of Sandhill Cranes arriving by the minute in the setting sun. The video below provides a sense of how it felt...

Don't just pass through the Great Valley on your next trip to California. Check out our valley and find out why we call it "Great". Two places to get information: the headquarters for the San Luis NWRC near Los Banos, and in a few short months, the Great Valley Museum on the west campus of Modesto Junior College. 

The title quote comes from Will Durant, and in its entirety reads "Civilization exists by geological consent, subject to change without notice".

Where the Sierra Nevada Rises from the Sea: Point Reyes National Seashore

Drake's Beach, with outcrops of Purisima Formation that reminded early sailors of Dover.

Around 30 million years ago major parts of Central California were in Southern California. It's about that "simple". Around 29 million years ago a major restructuring of plate boundaries was taking place along the Pacific Coast. A subduction zone (convergent boundary) that had influenced the California margin for nearly 200 million years, forming the granitic rocks of the Sierra, was changing over to something new. It was transforming, so to speak.

For many millions of years, oceanic crust and exotic terranes were carried eastward towards the continent, only to be forced beneath the edge of North America (subducted). Eventually the source of oceanic crust, the East Pacific spreading center, made contact with the convergent margin and subduction ended. Because of the relative motion of the two plate edges, a new fault system developed, the San Andreas, and a portion of Southern California began to move northwestward along the new fault. Such zones that divide crustal plates from one another are called transform boundaries. Granitic rock that had formed as part of the Sierra Nevada Batholith was sliced off from the south end of the province and was carried north several hundred miles (see below). The displaced granitic rocks are referred to as the Salinian Block.

The Point Reyes Peninsula is one of the more intriguing corners of California. It's connected to the California Coast Ranges after a fashion but it is a world apart. Tomales Bay, Olema Valley, and Bolinas Lagoon mark the location of the San Andreas fault. The epicenter of the infamous 1906 San Francisco Earthquake was close to Point Reyes, and offsets totaled close to 20 feet during the magnitude 7.8 seismic event.

The peninsula is protected from development as Point Reyes National Seashore, and is a haven for wildlife. During my visit several years back I captured my best shot ever of a California Quail. On our way to the beaches, we saw a herd of Tule Elk.

The Peninsula has several distinct geological sections. The mountainous terrain of Inverness Ridge is composed mostly of the granite and metamorphic rocks of the Salinian Block. Much of the western and southern parts expose sedimentary rocks of Miocene and Pliocene age. During the journey northwest from Southern California, the peninsula was submerged beneath the ocean waves. Active dune fields can be found along the extensive beaches of the peninsula.

Drake's Estero is an interesting feature. The branching arms of the bay suggest that it is a submerged river valley. The shallow water has proven to be a good spot for oyster farming, and the 80 year old business is embroiled in a battle with the park service over land-use issues.

Source: USGS (http://pubs.usgs.gov/of/2005/1127/)

From the headland of Point Reyes, Point Reyes beach stretches northward for around 10 miles, making it one of the longest stretches of sandy beach in Central or Northern California. As popular as it might have been, the fierce waves and very cold water make for uncomfortable water play.

The rocky headland where the lighthouse is located is composed of granitic rock and some of the overlying late Cenozoic sedimentary rocks. The lighthouse is visible from as far as 24 miles away, but fog obscures the view for around 140 days a year. Winds are nasty (highest recorded was 133 mph), and the temperature generally hovers between 50 and 60 degrees Fahrenheit all year.

Reaching the lighthouse requires descending 300 steps, but during the rare clear days, the spot is one of the best in California for whale-watching. Expect crowds on the nice days...

Steps leading to the Point Reyes Lighthouse

In the next post, we'll explore the more inland part of Point Reyes National Seashore, mainly Tomales Bay and Bolinas Lagoon.

Point Reyes Lighthouse, constructed in 1870

The Other California: Already off on a Tangent

It occurred to me while looking over my postcard post on the "usual" places of California that a discussion of places in California that are overlooked could also include a discussion of overlooked state symbols, especially in the context of geological significance. A lot of people know that the state flower is the California Golden Poppy (Eschsholtzia californica), and that the state bird is the California Quail (Lophortyx californica). Calling upon my students as a cross-section of our state's population (which they aren't, really), somewhat fewer know that our state mammal is not just a bear, but the California Grizzly Bear (Ursus californicus) which is probably the only state mammal in the United States that was actually extinct when it was designated (the last one was shot in 1922; it became the state mammal in 1953). Along with the California Condor (now why isn't the condor our state bird?), it was one of the last of the megafauna survivors in our state (more coming on that subject).

It takes people a little longer to recall our state mineral: it's gold of course, given the beginnings of our state in the 1850's in a massive Gold Rush that brought hundreds of thousands of migrants to the region. But what about our state rock? Our state gemstone? Our state fish, or fossil, our state Gold Rush Ghost Town, or our Silver Rush Ghost Town? Or our state soil? And what about our state tree (trees, actually)? I suspect the trees are pretty well known.

And what about our state song? I pretty seriously thought it was "California, Here I Come", but it isn't! A sampling from "I Love You California", by F.B. Silverwood:

Where the snow crowned Golden Sierras
Keep their watch o'er the valleys bloom,
It is there I would be in our land by the sea,
Every breeze bearing rich perfume.
It is here nature gives of her rarest. It is Home Sweet Home to me,
And I know when I die I shall breathe my last sigh
For my sunny California.

I love you, Catalina, you are very dear to me.
I love you, Tamalpais, and I love Yosemite.
I love you, Land of Sunshine, Half your beauties are untold.
I loved you in my childhood, and I'll love you when I'm old.

Really, how many songwriters could squeeze Tamalpais into a lyric?

More on these less familiar state symbols in another post. If you want to cheat and look ahead, the complete listing can be found here.