California v. II

… continued


About thirty million years ago, the trailing edge of the Farallon Plate began to disappear under North America in the shape of an inverted 90° wedge, beginning at the location of present-day Los Angeles, and proceeding northeast under the continent, leaving nothing but hot mantle where before was the cold, subducting oceanic plate.

Burial of the Farallon Plate

Burial of the Farallon Plate

Over the past twenty million years, that trailing edge has been crossing the Sierra Nevada region, and it’s traveled nearly as far north as Mount Lassen thus far, creating a great triangle between the trailing wings of the subducted Farallon Plate and the Pacific Plate.

With no more subduction to trigger the kind of volcanic activity characteristic of Mount Lassen and the Cascade Range to the north, the Sierra Nevada has transitioned into a new phase of plutonic activity. The hot, underlying mantle has pressed up through the great triangle, causing uplift and, as the uplifted dome has increased the surface area above, spreading. The spreading, in turn, has created grabens such as Owens Valley.

Though the stone that makes the Sierra Nevada was formed long before this uplift and spreading, it was this event, beginning about thirty million years ago, that actually gave rise to the Sierra Nevada that we know today. Still, there have been much more recent events that have contributed greatly to the general, large-scale structure of the range.

A New Age of Volcanism

This new incarnation of California lacks the Cascadian volcanism of its past, yet the existence of the eruption of the Long Valley supervolcano 760,000 years ago attests to the volatility of the present-day Sierra Nevada. It was an eruption 500 times the size of the 1980 Mt. St. Helens eruption and 30 times the size of the 1883 Krakatoa eruption, surpassed by only four eruptions over the last million years:

  1. Lake Toba, Sumatra, Indonesia
  2. Whakamaru, North Island, New Zealand
  3. Lake Taupo, North Island, New Zealand
  4. Yellowstone Caldera, Wyoming, USA

There are no stratovolcanoes along the spine of the Sierra Nevada, but there is evidence of something more terrible.

Localized Foundering of the Farallon Plate

As the trailing edge of the cold, dense Farallon Plate was detached from the supporting mass of any trailing oceanic plate, that trailing edge must have begun to sink — not merely as a caboose follows a train downhill, but rather more directly down, as it was no longer supported on its western boundary.

Delamination and Mantle Drip

Such a sinking mass must have pulled on the lithosphere above it, and possibly pulled the dense root of the Sierra Nevada downward and away from the mountain range. Once the trailing edge of the subducted plate passed, the detached root of the Sierra — being relatively dense — may have begun to sink more directly into the depths of the mantle, causing local downwelling.

Subsidence east of Fresno

Sinking mountains east of Fresno

Asthenospheric mantle flowed in to fill the gap where the Sierra’s root had been — probably liquefying under reduced pressure, and the Sierra, without the ballast of its dense root, became more buoyant, and began to rise, pulling even more asthenospheric mantle up with it, some of which would have liquefied. As magma, it would have injected itself into cracks in and around the thin Sierra block, ushering in the current phase of Sierra volcanism.

As the delaminated Sierra root descends into Earth’s mantle, it has created a local convection cell. The sinking root is causing downwelling in its wake, and pushing mantle rock downward and outward ahead of it. This downdraft appears to be causing subsidence in the Tulare Basin and the western Sierra adjacent to the basin.

As the displaced mantle rock is pushed aside, it then begins to rise, creating upward pressure at its edges — probably more along one edge, due to asymmetry. The upward pressure creates a local updraft, which may be adding to the uplift of the Sierra.

Further Reading:

Active foundering of a continental arc root beneath the southern Sierra Nevada in California

Watching Whales in the Sink

California v. I

It’s common knowledge that water is the bane of fire, but the Earth tells us a different tale.

The continents of Pangaea

The continents of Pangaea

Up to about 200 million years ago, at the dawn of the Jurassic Period, there was no California. It might be said that even North America didn’t exist. North America had then part of the supercontinent of Pangaea, which was about to break apart.

As ancient peoples once imagined their world an island in a great sea, so Pangaea was an island in a great sea. For eons, the rivers of Pangaea carried sediments to that sea, loading down the dense, cool crust beneath the waters. That crust, it turn, was floating upon an ocean of lithospheric mantle, but the crust was getting heavier and losing its buoyancy, until finally it gave way, and began to list like a ship giving in to the sea.

Around Pangaea, ocean floors began to dive beneath it for the same reason, leading to what we know today as the Pacific Ring of Fire, and the Triassic supercontinent began to fracture under the strain of the spreading triggered by the suction of ocean floor subducting into its perimeter.

Here on the eastern shore of the great ocean, the Farallon Plate was born out of the disintegration of Pangaea. As this young oceanic plate dove under Pangaea (and later Laurasia), the uppermost layer of the plate was scraped off and piled against the edge of the continent, and so Cascadia was born. Cascadia is that land commonly known today as the Pacific Northwest. When California was young, it was part of Cascadia.

The continent was pulled westward and stretched along its margin, giving rise to the forearc basins known today as the Puget Sound, the Willamette Valley of Oregon, and California’s Central Valley.

The water-loaded serpentine hydrated the rock beneath the continent, liquefying the rock and causing streams of melt to form. This led to the formation of a volcanic arc along the Pacific Coast, and deep below, the plutons that would eventually uplift to become the Sierra Nevada and Klamath Mountains of the present.

The hydrated magma streams that feed the volcanoes of Cascadia are not pacified by their water continent, but contrarily, rendered all the more volatile by the resulting steam, making for explosive releases of subterranean fire, not unlike the sudden expansion of a grease fire when fed with water.

Down in Cascadian California, there was no San Andreas Fault, nor any great granitic Sierra Nevada. These and other characteristic features of present-day California would arise as the trailing edge of the Farallon Plate began to disappear under North America.

To be continued …

Beware Anonymous Cheques!

… and keep your credit cards close to your vest!

… and Burn in Hell, Budget!

Keep your credit cards close to your vest!

Keep your credit cards close to your vest!

I just got a cheque in the mail for $9.95 to be paid to me. It’s a very official, professional-looking cheque, addressed to “California Resident”, and issued from “California Processing Center”. I was set to cash the damned thing, when my wife Carolyn — bless her observant soul — pointed out to me that I was being scammed. She showed me the small print on the back of the cheque:

By cashing this check I agree to a thirty-day trial offer in Just for Me. I understand that the $13.99 monthly fee will be automatically billed to the card I have on file at Budget unless I cancel my membership by calling 1-877-658-9097 before the end of the trial period …

From another blogger who nearly got suckered by the same scam: Beware: Budget Car Rental Autovantage $10 Check Scam

The Hungriness of Stuff

We previously reflected upon the intimate, multifaceted relationship between ancient man and fire, and considered how easy it would have been for a man such as Heraclitus to conceive of the idea that fire is the fundamental constituent of all matter.

Heraclitus was, after all, a subject of the Persian Empire, a land of fire worship, and the reputed cradle of alchemy. Alchemy is a practice of transmuting matter that depends greatly upon fire. It seems to be a natural—albeit mystical—offspring of the bronze age.

Perhaps after recognizing the ubiquity of fire, Heraclitus reflected upon the nature of fire, and came to this conclusion:

Burning Man effigy, Black Rock City, Nevada

Burning Man effigy, Black Rock City, Nevada

fire is hunger and satiety.


Fire is indeed a hungry phenomenon. It seems to exist exclusively to consume, though the light and heat it has provided us through the millennia make it much more than a consumer. Yet it remains an archetype of consumption. Is not combustion the primal hunger within us? Is it not our deepest physiological craving for the fuels of combustion: oxygen and carbon compounds?

But fire is obviously not equal to hunger, for as consumption, it is also the satisfaction of its hunger.

Seeing everything around us as governed by this paradox, one can easily see the function of fire in the philosophy of Heraclitus. Heraclitus taught that the world is governed by a harmony of opposites. Recognizing that harmony, he saw wisdom in the working of things, but it was a harmony of war, of hunger. Whatever equilibrium he could see was a dynamic, cyclic equilibrium under tension. To Heraclitus, fire must have seemed fundamental both literally and metaphorically.

The Biology of Fire

What is the color of life?

Green. Certainly, most observers would agree.

Yet when one considers what the green represents, one might not remain so certain. Green is the color of photosynthesis. It is therefore the color of the conversion of light energy to chemical potential energy—stored energy.

Fire Poppy

Fire Poppy: only appears immediately after a fire.

Isn’t life better seen as the active changes in things, rather than the potential for those things to change? What life would there be if nothing ever actually changed?

Life itself is in the consumption of the potential—the combustion of the products of photosynthesis. The actual life is in the burning, that is, the respiration.

A fire seems alive. It respires just as we do, needing the same oxygen and exhaling the same carbon dioxide. it is that same phenomenon—combustion, in the form of cellular respiration, that gives us life as aerobic creatures.

Not to take anything away from water or carbon, which to some extent all life seems to require; it’s specifically combustion that gives us life. Of course fire is a universal phenomenon of which combustion is but one example. Ultimately, it is fire that gives us the building blocks of life—elements such as oxygen and carbon; but for now let us stick with combustion.

Spontaneous combustion: It happens all the time.

Spontaneous combustion: It happens all the time.

The food that we consume is used to feed the internal combustion engine within us, just as a campfire consumes wood; just as a car’s internal combustion engine consumes petroleum. Like the life that we know, the fire grows as it consumes, and as it grows, it travels. Not only does an individual fire grow; some even bear children: they spit out fire children that rise on the parents’ convective currents and fly outward to begin lives of their own.

Perhaps you have seen a fire sleep, mimicking the stars in the sky with its constellations of red coals. Or maybe you’ve watched the mesmerizing dance of a fire. Maybe you listened to its crackling song while it danced. Was it a song, or was that the sound of its infernal molars crushing its food? Did you hear it breathe? It breathes in and it breathes out.

Have you ever suffocated a fire? Funny how that can seem a little like a killing.

Fire and Water

Here in California, we have two seasons: a season of water and a season of fire. The fire season generally begins when the rains cease, which is typically in mid-April—say, Tax Day. The fire season continues beyond the end of summer into the warm California autumn, until the rains return—around about Halloween.

I remember, as a matter of fact, the rains returning last Halloween, while trick-or-treating with the kids. I remember how warm that first rain was. It even seemed refreshing.

The old Gaelic year ended on Halloween, so I hear. In California, the return of the rains is obviously a big deal, but I’m not sure it ought to mark our new year (as though it represented a rebirth).

I say I’m not sure, but it probably should. It’s ironic because the leaves haven’t even fallen from the trees yet by Halloween, but one can watch the world being slowly reborn through the mild winter months. February and March bring progressively more glory, but it all begins with the first rain in autumn.

My doubt has to do with the role of the sun in all this. To base the rebirth solely upon the return of the rains seems to disrespect the importance of sunlight in bringing about life, but I suppose it’s obvious enough that this is all made possible by the fact that the sun is somewhat ever-present around here.

Pink Floyd and Thoreau

I was just listening to the Pink Floyd song “Time” the other day, when three lines of the song struck me:

You fritter and waste the hours in an off hand way …
You are young and life is long and there is time to kill today …
Hanging on in quiet desperation is the English way

I had long been cognizant of a connection between the last line and something Henry David Thoreau wrote in Walden:

The mass of men lead lives of quiet desperation

… but this time I suddenly recognized two other connections between this song and Thoreau’s masterpeice:

Our life is frittered away by detail … Smplify, simplify.

as if you could kill time without injuring eternity.

I wonder what Roger and the boys had been reading when they wrote “Time”. Though I don’t see the same depth in the song that can be found in Walden, these verbal coincidences make me wonder what were their inspirations.

My College Sweethearts

It suddenly occurs to me that I wrote my first love poem 26 years ago. I wrote it in Apple ][ BASIC. I just had to tell her how fine she looked on that low-res green screen. What beautiful pictures that green screen could make of my sweet little Trigah.

Trig! That bitch was the bane of my senior year. All those mysterious identities to be memorized—what for? For college? I wasn’t even finished with high school, and I was already sick of college.

The school counselor had a talk with my math teacher. He had seen me with Trig, and he could tell that we weren’t meant for each other. The counselor told my parents to steer me clear of anything involving Trig, Math, or anyone like them. They just weren’t my type.

But my Apple ][+ showed me her beauty—like the stars: a little coefficient here, or an angle multiplier there, and her sines and cosines suddenly had a beauty—a meaning—all their own.

By the time I met her again in college, I couldn’t get enough of her. How she had grown!

That’s right: college. I couldn’t find anything else to do with myself, so there was no way out of it. So I enrolled in the local community college.

But college had little or nothing in common with college prep. I could finally meet subjects on their own terms—not on behalf of college preparation.

That’s where I met Calculus. She was beautiful too, in a new way, and I loved her too. I wrote little love programs to her, even while I was still writing poems to Trig. Sometimes I would write one poem for both of them. I wonder whether they knew.

Loving them both was more fulfilling than loving just one or the other. Without one in my life, the other seemed—incomplete.

Their charms were so—complementary.

Then there was Diffy Q., and Vectora Nalysis—and Linnea L. Gebra. They were each beautiful in new, refreshing and surprising ways. I loved them too.

I loved them all.

The Source

The theme, or motto, of this blog has its source in an essay of Plutarch entitled “On Listening to Lectures.” Here’s a translation of Plutarch’s actual words:

The correct analogy for the mind is not a vessel that needs filling, but wood that needs igniting — no more — and then it motivates one towards originality and instills the desire for truth.