One of California's Rarest Ecosystems: The Serpentine Soils of the Red Hills

 The Red Hills are blooming right now, so I am posting an abridged version of my post from May 21, 2021 explaining the geological conditions that formed the unique landscape.

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. 

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.

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.

Life in a Harsh Environment: Spring Wildflowers in the Red Hills Area of Critical Environmental Concern

Ceanothus, Poppies, and Goldfields in the Red Hills area of the Sierra Nevada foothills.

Welcome to the Red Hills "Area of Critical Environmental Concern", a 7,000 acre preserve in the Sierra Nevada foothills near the village of Chinese Camp. We paid a visit today to see what flowers were out and about in this horrific drought year when much of the state has received hardly a quarter of the normal amount of rainfall. It's a fascinating area to explore, despite the somewhat plain appearance of the hills. The interest lies in the struggle for life in this tough environment.

Brodiaea, or Blue dicks, Dichelostemma capitatum. Can you see the tiny mite in the flower?

It's not exactly harsh as far as the climate is concerned. Sure, it gets hot in the summer and the rain falls only in the winter and spring. But it rarely gets cold enough for snow, and the nearby hills include thick forests and brush. In the Red Hills, one is struck by the near total lack of grass covering the hillsides. Although oak trees are common throughout the region, few if any take root in the Red Hills. And there are sharp vegetational boundaries. The oak woodland and grasslands simply end, and the barren ground begins.

Indian Paintbrush

The problem is the soils. The underlying rocks are composed of serpentine and other ultramafic rocks derived from the Earth's mantle, the thick layer that lies beneath the oceanic and continental crust. The mantle rocks are rich in iron, nickel, chrome, and other metals that are toxic to most plants. The soils are also deficient in nutrients that plants generally need.

I don't know these diminutive flowers. Any ideas? I'm guessing Baby Blue Eyes (Nemophila menziesii) PS: Nope, it's
Bird's Eyes (Gilia tricolor), thanks Russ Cary.

These tough conditions mean that many plants can't grow on these soils, but others that are usually crowded out by grass and weeds can either tolerate the serpentine soils, or even thrive. Some 250 plants have been found in the Red Hills, including a number of endemics that are not found outside the serpentine exposures.

Five spot (Nemophila maculata): It's strange, but for all the years we've been coming out here, I have never noticed this species before. It is quite pretty!

For years the Red Hills were an abused landscape. Despite the proximity of the Mother Lode gold veins, very little gold was found in the hills (serpentine is not a gold-bearing rock). Nothing of value could be grown in the soils, and so the land was used as an illegal garbage dump, shooting range, and off-road vehicle course. As the uniqueness of the hills became better known, the Bureau of Land Management acted to protect and clean up the region. Today there are trails and parking areas for visitors. It is especially popular in the spring when the wildflowers are at their best. As mentioned before, the year has been horrifically dry, and we are indeed in the midst of the worst drought ever recorded. The flowers are getting started, but it remains to be seen whether they will thrive through the spring (there is a possibility of some rain this week).

As we left, we saw a particularly rich patch of poppies and brodiaea, but such richness was the exception. For the most part, the flower show hasn't really started yet (if it starts at all).

We left the Red Hills and headed south on Highway 49 on the way to Marshes Flat Road. Along the way I took a deceptive picture (above). Yes, it sure looks like an explosion of California Poppies. It's enough to cause one to say "What drought?". But take a look at the larger context of the picture (below)...

The flowers thrive because runoff from the pavement gives the soil the extra moisture they need. There are few flowers beyond the edge of the highway. Still, the color was beautiful, and I hope the rain this week will keep the show going a little bit longer before the long, hot and dry days of summer.

There were more (and different) flowers on Marshes Flat Road. We'll see those in another post.

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.