Red Hills Area of Critical Environmental Concern (Couldn't the Bureaucrats Just Call it a Preserve?): Spring Update

Welcome to one of the most unique ecosystems and habitats in California's wealth of incredible places. It was ignored initially by miners in the region because it had no gold (the Mother Lode is a scant two miles away).  It was more recently ignored because it had no grass for grazing and poor soils incapable of growing anything "useful". The Bureau of Land Management, tasked in its early days of giving away land by way of the Homestead Act couldn't give the free acreage away at all. All but ignored by federal government, the absentee owner, it became an unofficial garbage dump, unauthorized shooting range, and unsanctioned off-road vehicle route. 

Why were the soils so poor in nutrients and toxic to plant growth? It was the underlying rocks: the serpentine and other ultramafic rocks associated with the Melones Fault in the Sierra Nevada Mother Lode. The soils developed on these rocks were severely deficient in important macronutrients, and contaminated (so-to-speak) by toxic metals. Most plants, including most grasses, cannot survive in these soils. Some select species tolerate the soils, and a few rare ones thrive. It is literally a different world, and as you can see in the picture above, the change is abrupt, as the prairie grasses and oak woodland suddenly give way to ceanothus or buckbrush and gray pine.

By the late 1980s the Bureau of Land Management, the federal agency in charge of the Red Hills area, belatedly recognized (with the encouragement and assistance of community and environmental activists) the unique nature of the ecosystem here, and declared it an "Area of Critical Environmental Concern", the kind of a designation that only a bureaucrat could love. It turned out that this landscape contained a large variety of endemic species found almost nowhere else, including a unique fish species, the Red Hills Roach (Lavinia symmetricus). Clean-ups were organized, and minimal tourists facilities (trails, parking areas, vault toilets, and a nature trail) were constructed. 

Bitter root (Lewisia rediviva)

For much of the year, especially in the hot dry summer, there is little to recommend about the Red Hills. Most of the plants are dead and gone to seed. But for a few months during the cooler wetter spring season, the hills come alive. It turned out that many of the plants adapted to living in these soils produce a vivid display of color when they bloom.

California Goldfields (Lasthenia californica) and scattered poppies

We took a bit longer to make our way up to the Red Hills this year, in large part because there hasn't been more than a spatter of rain since December. We are in the midst of another year of lingering drought. But in the end we decided to have a look, and although it came nowhere near the pyrotechnics of color of past years, there was more than enough to make for a satisfying excursion.

Poppy, a flower that seems able to grow in just about any environment California can fling at it.

Enjoy a little bit of color!

Monkeyflower (Erythranthe sp.)

Blue Dicks (Brodiaea)

The parking area and trailhead at Red Hills ACEC

Poppy sp. and Blue Dick (Brodiaea)

Serpentine

The Red Hills got their name from the red soils that develop on the ultramafic rocks, including serpentine. The rocks are rich in iron, thus the red color, but fresh surfaces of the rocks are generally shades of green, as can be seen above.

Paintbrush sp.

Lupine sp.

Lupine sp.

The Red Hills Area of Critical Environmental Concern is in the Sierra Nevada foothills near Chinese Camp off of Highway 120. If you want to learn more, or pay a visit, information about the Red Hills can be found on this BLM website, and the trail and road map can be found here.
 

California's Rarest Ecosystems: The Serpentine Soils of the Red Hills (Part Two of a Two-part Miniseries)

 

Imagine a world turned upside down and inside out. A place where the underworld realm is exposed to view, where all is out of equilibrium. It sounds like the introduction to a dystopian horror movie, but in this case, it is a description of one of the truly rare and unique ecosystems in California: the serpentine soils. 

This is the long-delayed second part of my two-part miniseries on rare ecosystems. Part one on the prairies and vernal pools was published back in April.

The Red Hills Area of Critical Environmental Concern is a rather clumsy name for one of the most unique places in all of California. It comes by the name righteously, as can be seen in the Google Earth image above. The soils have a distinct red-brown color, even though the serpentine-rich rocks they come from are generally green or black in color. And these are truly alien rocks. They are not part of the surface realm; they are the materials of the earth's depths, far below the crust that we live on. The earth's mantle lies at depths of 15 to 40 miles beneath the surface and is composed of iron and magnesium-rich minerals like olivine and pyroxene. These minerals may be stable deep within the earth's interior, but if they are exposed at the earth they are out of chemical equilibrium and subject to rapid reactions with oxygen, water, carbon dioxide, and acids in soils. The iron quite literally rusts during oxidation.

The thing about soils rich in iron and magnesium is that they are poor in macronutrients like potassium and calcite, and include some toxins like selenium or nickel. The vast majority of plants cannot tolerate these chemical conditions. But there are a few.

At the west end of Red Hills the oak woodland gives way to a gray pine-ceanothus scrubland

The change is stark. Driving up Red Hills Road from the west, one passes through typical foothills oak woodlands, with a thick covering of grass. And then just like that the grass disappears along with the oaks. One enters an area dominated by Buckbrush with the occasional Foothills Pine (Gray Pine). In many areas, barely any vegetation covers the rocks at all.

The region was long seen as having no particular value. The ultramafic (mantle-derived rocks) were related to the gold-bearing lodes, but rarely had any valuable ores in and of themselves. Despite the Homestead Act in the late 1800s that sought to give citizens free land in the west, there were no takers in the Red Hills. No useful crops could be grown on the soils, which was a requirement for owning the property. For many decades the Red Hills were used as a de facto garbage dump and shooting range.

By the late 1980s the Bureau of Land Management, the federal agency in charge of the Red Hills area, belatedly recognized the unique nature of the ecosystem here, and declared it an "area of critical environmental concern". Clean-ups were organized, and minimal tourists facilities (trails, parking areas, vault toilets, and a nature trail) were constructed. Today the park (why not just call it a park, after all?) is a local favorite for wildflower enthusiasts, birdwatchers, and hikers, especially in the spring.

So what is the geologic story of this strange and wonderful landscape?

The Mother Lode is famous as the source of the ores during the Gold Rush in 1848-53, and many people know of the association of quartz veins with the gold. What is less known is that the Mother Lode consists mostly of metamorphic rocks like slate, greenstone, and marble, not the granite that is found in the higher parts of the Sierra Nevada. These metamorphic rocks are the twisted and baked remains of sea floor muds and silts, lime from tropical reefs and shelves, and volcanic rock from the oceanic crust. These collections of crustal rocks (called "exotic terranes") were transported across the Pacific Ocean and slammed (in the geologic sense; they moved at maybe 2 inches a year) into the western edge of the North American continent, mostly in the late Paleozoic and Mesozoic eras (the Mesozoic era, from around 251 to 65 million years ago, is best known as the "age of the dinosaurs"). The different terranes are separated from one another by major fault systems.

California Goldfields (Lasthenia californica)

The rocks of the Red Hills were part of the huge fault systems and included slices of the earth's mantle, consisting of the dunite and peridotite mentioned above. The original mantle rocks were mostly metamorphosed into serpentine on their upward journey along the fault systems.

Blue Dicks (Brodiaea) and Poppies

Serpentine (or more properly serpentinite) was declared the California State Rock in the 1960s, in part for its association with asbestos, which is a fibrous crystal form of serpentine. Asbestos was a "wonder mineral" from at least Roman times, as it was fireproof, and could be woven into a fabric. As fire insulation it no doubt saved many lives, but there was a cost. Those who were constantly exposed to asbestos were far more likely to contract a deadly disease called mesothelioma. It is now a cottage industry for people in the business of removing asbestos from older buildings.

There was a political brouhaha in 2010 when some groups tried to change the state rock to something else, but geologists objected on the grounds that it was an appropriate symbol of the state due to the research value of having mantle rocks at the surface, and the value as an ore for other important metals such as chromite (used in armor and stainless steel), and mercury (used original to separate gold from its host ore). The proposed bill was never voted on.

The Red Hills are semiarid with only a few creeks that dry up quickly as the summer progresses. But a few small springs and pools persist through the year and in those pools is an endemic fish, the Red Hills Roach, a distinct subspecies of the California Roach. It is found nowhere else in the world. We saw some of them a few weeks ago during our visit, but the video below is from an earlier, wetter year.

The rest of the photos are some of the flowers we saw this year, some old friends, and one or two new discoveries.

Poppies

Five Spot (Nemophila maculata)

Monkeyflower (Erythranthe sp.)

Bitter root (Lewisia rediviva)

The last flower was one we've not noticed before. It seems to be a Fort Millers Clarkia, but I am open to correction!

Fort Miller Clarkia (?) (Clarkia williamsonii)

There are just a few flowers left in the Red Hills as of last Friday, but to see the spectacular show you'll need to wait until next spring. But...the rocks are always there!

The Red Hills Area of Critical Environmental Concern is in the Sierra Nevada foothills near Chinese Camp off of Highway 120. If you want to learn more, or pay a visit, information about the Red Hills can be found on this BLM website, and the trail and road map can be found here.

Damning Del Puerto Canyon, a Geological and Natural Treasure in our County

I awoke this morning mildly astonished to see my own words making up the headline of a Modesto Bee article about a proposed dam in Del Puerto Canyon, a deep gorge cutting into the heart of the Diablo Range in the western part of Stanislaus County. Del Puerto is one of the most unique landscapes of California's Coast Ranges, and as I noted, a geological and natural treasure. I was hugely dismayed to find that a proposal exists to build a large reservoir in the lower canyon, and my email to a colleague ended up being quoted in the Modesto Bee article linked above (hence my surprise at being quoted; I wasn't directly interviewed). The article accurately describes my concerns about the project. There are large landslides in the lower canyon that canyon that would almost surely be reactivated (or accelerated; they show evidence of recent motion) if the base is inundated by lake water. There are definite seismic concerns, as a probable active fault lies just east of the dam site. But my biggest concern is the effect the dam will have on the natural environment of the canyon.

The environmental impact report was published recently (read it here.). Comments on the Environmental Impact Report can be made at a public meeting from 4 p.m. to 6 p.m. Jan. 15 at the Hammon Senior Center, 1033 W. Las Palmas Ave., in Patterson. Written comments will be accepted until Jan. 27 at Del Puerto Water District, 17840 Ward Ave., Patterson 95363. If you appreciate the intrinsic value of our precious local canyon, I hope you will comment and make your voice heard.

I've written often about Del Puerto Canyon over the years (see many of the articles here), and to give you a feel for the unique nature of the canyon, I'm adapting an article from last May.

The strange and alien landscape in upper Del Puerto Canyon.

California has some really strange landscapes. A state that has beaches, mountains, volcanoes, forests, and deserts is going to offer many perspectives of the complex geological influences on the state. But for alien and otherworldly, few places in the state can compare to the journey you take when you follow Del Puerto Canyon from its mouth in the Great Valley to the headwaters in the Diablo Range. It's a journey into the middle of the world.

"Del Puerto" refers to "The Gate", the constriction of hard sandstone at the mouth of the canyon. This will be the site of the proposed dam. It will be more than 200 feet high.

I guess I should be a bit more specific. We journey to rocks that had once been part of the Earth's mantle, the 1,800 mile thick layer that lies just beneath the thin crust (3-50 miles thick). We can't reach the core of the planet, because no one can (despite sci-fi movies that say otherwise). Since mantle rock is very hot and is subject to convection, it is at least conceivable that the rocks we are exploring have once been close to the Earth's core.

This is an active landslide that will be partially inundated by the proposed reservoir. I am concerned about the effect of adding water to the slip plane. California's first discovery of dinosaur bones was at the top of this slope.

So how does one explore the Earth's mantle? Well, first one has to get through the crust, and the thinnest crust is that which makes up the ocean floors. It's nominally composed of basalt, but the details are more complex.

In Del Puerto Canyon, the ocean floor is covered by...a bit of sediment. About 25,000 feet of it! The sediments poured off the mountainous edge of the continent during the later part of the dinosaur era, the Cretaceous Period. There was a huge subduction zone that formed as oceanic crust plunged into the mantle beneath the edge of the North American continent. This so-called Cascadia Subduction Zone caused volcanoes to form where the Sierra Nevada is today, but the area offshore of the volcanic arc, the forearc basin, collected sediments. As the sediments accumulated, they pressed the crust downward and even more sediment piled on top. Eventually the layers reached a thickness of five miles.

The basin collected fossils as well. There were the usual shells of clams, snails and ammonites, a variety of shark teeth, and three groups of seagoing reptiles, the plesiosaurs (think Loch Ness), ichthyosaurs (think reptilian version of a dolphin), and 35-foot-long mosasaurs (think "swim for your life!"). Even dinosaur fossils have been found. The first dinosaur ever found in California, a Saurolophus, was discovered in the lower reaches of Del Puerto Canyon in 1935.

Eventually, one will reach the base of the oldest sediments, and encounter the ocean crust itself. Faulting obscures some of the relationships, and so in the picture below we see some of the oldest sediment on the right (somewhat brownish shale) and basaltic/andesitic volcanic rock on the left (greenish gray), separated by a fault. The volcanic rocks are harder, and the canyon takes on a more rugged aspect as we climb higher into the mountains.

The Coast Ranges of California are one of the youngest mountain systems in the world, having been uplifted mostly in the last 3 million years or so. The streams in this dry environment have not been able to downcut as fast as the mountains are rising, so they flow much of the way over bedrock. There are few floodplains in these mountains.

The water flows almost year-round and thus the canyon is a critical habitat for all kinds of wildlife. Dozens of mammals and reptile species are known, and nearly 200 bird species have been observed here.

Oceanic crust is basaltic in composition, but there are differences at depth. On the ocean floor, basalt flows form "pillows", globular masses of the volcanic rock. Beneath the pillow basalts, basaltic dikes fed the eruptions. Dikes occur when volcanic rock fills cracks and fissures in the surrounding rock. Since the surrounding rock is also dike material, the entire layer, a mile or two thick, is made of vertical sheet dikes. Feeding these dikes were magma chambers composed of...basalt! But some of the basalt was left at the base of the oceanic crust where it then cooled slowly to form a sparkling crystalline rock called gabbro. The entire suite of rocks is called an ophiolite sequence. The Coast Range Ophiolite sequence in Del Puerto Canyon is considered to be the second best exposed in the state, behind the Point Sal Ophiolite in southern California.

There is a spot in one of the most rugged parts of the canyon to investigate the gabbro where it was pierced by a vein of quartz (below). People have looked for gold here, but I doubt they found any.

Just a few more miles up the canyon we penetrate the uppermost part of the mantle. The rock originally consisted of ultramafic minerals like olivine and pyroxene, but here the rock has been metamorphosed into serpentine, California's state rock. The rock was sheared and faulted on its way to the surface, leaving shiny green and black polished surfaces (below).

And then we are there. In the uppermost part of the canyon, we reach the netherworld of mantle rock that was far less altered, so it retained some of its original appearance. In places we can see olivine and pyroxene crystals, as well as grains of chromite. These ultramafic rocks contain few nutrients needed by plant life, so only a few species can tolerate living on these slopes. Gray pines are among them, grasses generally are not. There are a number of wildflower species endemic to California that can be found here.

Looking at these shattered broken rocks from very deep in the Earth, one imagines hell freezing over. The forges of the demons and devils lie frozen in place, to be slowly removed by earthly weathering. They try to invade the surface realm, but they are defeated by the forces of the heavens, the water and ice falling from the sky.

It may have been a metaphorical battlefield, but in the end there is great beauty in the rarity of the flowers, plants and animals that thrive, or at least tolerate the conditions in the upper canyon.

Del Puerto Canyon is traversed (slowly) by Highway 130, originating in Patterson on the floor of the Great Valley. It can also be reached by way of Mines Road out of Livermore, a winding road out of the San Jose area over Mt. Hamilton and the Lick Observatory complex. It is not a fast way to go!

I know that there is a need for water in the Central Valley. But no matter how many dams get built, there will never be enough to meet the expressed needs and desire of agribusiness. But I feel that we need to keep some of the wild places, and Del Puerto is one of those especially unique places to learn about our planet. I hope you will make your voice heard about this project.

What to do on a Saturday? Let's Go to the Middle of the Earth (via Del Puerto Canyon)!

The strange and alien landscape in upper Del Puerto Canyon.

California has some really strange landscapes. A state that has beaches, mountains, volcanoes, forests, and deserts is going to offer many perspectives of the complex geological influences on the state. But for alien and otherworldly, few places in the state can compare to the journey you take when you follow Del Puerto Canyon from its mouth in the Great Valley to the headwaters in the Diablo Range. It's a journey into the middle of the world. Our Geology Club made the trip a few weeks ago as an ending of the semester celebration. Odd way to celebrate? Did you simply party? We traveled half-way to the center of the planet!

"Del Puerto" refers to "The Gate", the constriction of hard sandstone at the mouth of the canyon.

I guess I should be a bit more specific. We journeyed to rocks that had once been part of the Earth's mantle, the 1,800 mile thick layer that lies just beneath the thin crust (3-50 miles thick). We couldn't reach the core of the planet, because no one can (despite sci-fi movies that say otherwise). Since mantle rock is very hot and is subject to convection, it is at least conceivable that the rocks we explored had once been close to the Earth's core.

So how does one explore the Earth's mantle? Well, first one has to get through the crust, and the thinnest crust is that which makes up the ocean floors. It's nominally composed of basalt, but the details are more complex.

In Del Puerto Canyon, the ocean floor is covered by...a bit of sediment. About 25,000 feet of it! The sediments poured off the mountainous edge of the continent during the later part of the dinosaur era, the Cretaceous Period. There was a huge subduction zone that formed as oceanic crust plunged into the mantle beneath the edge of the North American continent. This so-called Cascadia Subduction Zone caused volcanoes to form where the Sierra Nevada is today, but the area offshore of the volcanic arc, the forearc basin, collected sediments. As the sediments accumulated, they pressed the crust downward and even more sediment piled on top. Eventually the layers reached a thickness of five miles.

The basin collected fossils as well. There were the usual shells of clams, snails and ammonites, a variety of shark teeth, and three groups of seagoing reptiles, the plesiosaurs (think Loch Ness), ichthyosaurs (think reptilian version of a dolphin), and 35-foot-long mosasaurs (think "swim for your life!"). Even dinosaur fossils have been found. The first dinosaur ever found in California, a Saurolophus, was discovered in the lower reaches of Del Puerto Canyon in 1935.

Eventually, one will reach the base of the oldest sediments, and encounter the ocean crust itself. Faulting obscures some of the relationship, and so in the picture below we see some of the oldest sediment on the right (somewhat brownish shale) and basaltic/andesitic volcanic rock on the left (greenish gray), separated by a fault. The volcanic rocks are harder, and the canyon takes on a more rugged aspect as we climb higher into the mountains.

The Coast Ranges of California are one of the youngest mountain systems in the world, having been uplifted mostly in the last 3 million years or so. The streams in this dry environment have not been able to downcut as fast as the mountains are rising, so they flow much of the way over bedrock. There are few floodplains in these mountains.

The water flows almost year-round and thus the canyon is a critical habitat for all kinds of wildlife. Dozens of mammals and reptile species are known, and nearly 200 bird species have been observed here.

Oceanic crust is basaltic in composition, but there are differences at depth. On the ocean floor, basalt flows form "pillows", globular masses of the volcanic rock. Beneath the pillow basalts, basaltic dikes fed the eruptions. Dikes occur when volcanic rock fills cracks and fissures in the surrounding rock. Since the surrounding rock is also dike material, the entire layer, a mile or two thick, is made of vertical sheet dikes. Feeding these dikes were magma chambers composed of...basalt! But some of the basalt was left at the base of the oceanic crust where it then cooled slowly to form a sparkling crystalline rock called gabbro. The entire suite of rocks is called an ophiolite sequence. The Coast Range Ophiolite sequence in Del Puerto Canyon is considered to be the second best exposed in the state, behind the Point Sal Ophiolite in southern California.

We stopped in one of the most rugged parts of the canyon to investigate the gabbro where it was pierced by a vein of quartz (below). People have looked for gold here, but I doubt they found any.

Just a few more miles up the canyon and we penetrated the uppermost part of the mantle. The rock originally consisted of ultramafic minerals like olivine and pyroxene, but here the rock has been metamorphosed into serpentine, California's state rock. The rock was sheared and faulted on its way to the surface, leaving shiny green and black polished surfaces (below).

And then we were there. In the uppermost part of the canyon, we reached the netherworld of mantle rock that was far less altered, so that it retained some of its original appearance. In places we could see olivine and pyroxene crystals, as well as grains of chromite. These ultramafic rocks contain few nutrients needed by plant life, so only a few species can tolerate living on these slopes. Gray pines are among them, grasses generally are not. There are a number of wildflower species endemic to California that can be found here.

Looking at these shattered broken rocks from very deep in the Earth, one imagines hell freezing over. The forges of the demons and devils lie frozen in place, to be slowly removed by earthly weathering. They tried to invade the surface realm, but they were defeated by the forces of the heavens, the water and ice falling from the sky.

It may have been a metaphorical battlefield, but in the end there is great beauty in the rarity of the flowers, plants and animals that thrive, or at least tolerate the conditions in the upper canyon.

We turned around and headed back to more familiar habitats.

Del Puerto Canyon is traversed (slowly) by Highway 130, originating in Patterson on the floor of the
Great Valley. It can also be reached by way of Mines Road out of Livermore, or  a winding road out of the San Jose area over Mt. Hamilton and the Lick Observatory complex. It is not a fast way to go!