The Volcano Behind Oakland (redux)

Round Top crater, tilted 90° to right, and quarried.

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The Volcano Behind Oakland (redux)

I think I have settled on the epitaph for my tombstone: Have Fun and Be Kind. Actually, while I concede the certainty of mortality, I don’t really want a tombstone. I would prefer that my lifeless body be cremated and my bones crushed, so my powdery remains could be scattered at sea, perhaps in Bodega Bay following my father (or further out if the charter boat captain isn’t too stingy about using fuel). Then the gritty grey plume of my exiting ghost would settle out as a thin dusting on the muddy surface of the sea floor, and in time my ashes would get pressed into a thin-banded shale or mudstone of future millennia.

The only uncertainty about human extinction is its timing: Will it occur in the distant future when the sun expands into a Red Giant and consumes the inner planets, or will it be an unnecessarily premature self-inflicted demise by some combination of war (whether radioactive or merely with firearms), environmental exhaustion and climate change? I suspect humanity will select option B, but — through the magical power of denial — conceptualize the experience as victimization by unanticipated natural catastrophes. In any event, I do not find the inevitability of human extinction to be regrettable. Humanity is but one of many simultaneous and transitory expressions of Life On Earth, and this earth is only a minute speck of an unimaginably vast universe that can obviously sprout life. So relax, the earth and the universe will carry on majestically without us; we are as unnecessary to them as the dinosaurs were.

Like the animals and plants at the time of the dinosaurs, the life forms of today may become the coal and petroleum fueling the pottery kilns of future primitives, like the Anasazi, or the industries of future technological societies, if any.

I find the contemplation of geologic history, and the learning about its particulars on those parts of earth’s surface where I circulate, to impart a mental serenity like that gained by viewing vistas from mountaintops, or out in the expanses of the Great Basin and the Colorado Plateau of the American West.

The North American continent moves west across the surface of the globe because of the widening of the Atlantic Ocean caused by the magmatic extrusion of new rock from a linear spreading center that runs down the middle of that ocean basin from the Arctic to the Antarctic.

The western edges of the American continents ride over the eastward-moving heavier tectonic plates supporting the Pacific Ocean, and which lie east of a series of north-south trending spreading centers. The eastern edges of the Pacific Ocean plates colliding into the American continents plunge into the earth, or subduct, to melt under the weight of those continents’ westward advance.

A Pacific spreading center, whose northern end was tilted to the east relative to its southern end, began to subduct under North America 30 million years ago (30 Mya), in what is today Southern California. Faults perpendicular to this spreading center extended westward (with a tilt to the north) from its northern and southern extremities. As this spreading center was overridden by the western edge of North America, it caused that portion of the overlying continent that was west of the buried spreading center to break off and begin sliding to the north, and west. The line of this fracture lengthened as the subduction of the spreading center continued, and this was the origin of the San Andreas Fault (SAF).

The north-south trending SAF lies near the California coast. By 20 Mya, the northern end of the SAF had extended north into Central California. By 10 Mya, the northern end of the SAF was near Monterey Bay, and today it is in Northern California at Cape Mendocino, which is the westernmost extent of the California coast.

The northern end of the SAF is a triple point from which emerges the Mendocino Fault, which runs perpendicular to the SAF and westward out to sea. Slippage along both the SAF and the Mendocino Fault is such that earth on the opposite side of the fault is seen to move to the right. The land just north of the triple point is colliding eastward into North America, and the land (ocean floor) just south of the triple point and west of the SAF is colliding northward into the subduction occurring north of the triple point.

The confluence of tectonic motions at the triple point generates sufficient geologic pressure and heat to cause vigorous seismic activity and volcanism in its vicinity. For over 20 million years, volcanoes have preceded the northward advance of the northern triple point of the SAF. The Neenach Volcano, in Los Angeles County, erupted 23 Mya and was subsequently split by the SAF so that its western half now lies 314 km (195 miles) to the northwest in present day Pinnacles National Park (which is east of the Salinas Valley and 130 km, or 80 miles, south of San Jose). From 10 Mya to 9 Mya, volcanoes erupted in what are today the hills east of the cities of Oakland and Berkeley. About 2.4 Mya, numerous volcanoes were active in the Clear Lake Volcanic Field, which lies north of the counties of Napa and Sonoma. The most recent eruptions in the Clear Lake Volcanic Field occurred about 11,000 years ago around Mount Konocti. Today, the magma chamber beneath the Clear Lake Volcanic Field is exploited to extract geothermal energy by the largest complex of geothermal power plants in the world.

The volcano in my neighborhood is Round Top, which is uphill from the city of Oakland in what is today a public park, the Robert Sibley Volcanic Preserve.

Between 16 Mya and 14 Mya, the San Francisco Bay Area was part of a marine basin a mile deep (1.6 km). The marine sediments of this basin are today lithified in the rocks of the Claremont Formation. The ocean floor of this basin was uplifted, between 14 Mya to 12 Mya, and the sedimentation of this period occurred in shallow water. This seafloor was lifted above sea level some time after 12 Mya, and for 2 million years the land was an alluvial plain accumulating sediments from streams running east from a chain of coastal mountains, which were situated where the San Francisco Peninsula and the Golden Gate Bridge (the entrance to San Francisco Bay) are today. This plain dipped toward the east to meet the shore of an inland sea near the present day towns of Orinda and Lafayette. These terrestrial sediments, from 12 Mya to 10 Mya, were lithified into the rocks of the Orinda Formation.

The Round Top volcano erupted many times between 10 Mya and 9 Mya, spreading thick layers of basalt lava over the layered stream sediments and gravels of the Orinda Formation. The surrounding countryside was a low plain with lakes, so volcanic ash ejected during eruptions would fall into water to settle out in thin, uniform layers, which were subsequently compacted into finely-banded rock. Ash and cinders also fell on dry land, and this too was eventually compacted into rock. Between periods of volcanic activity, sedimentation occurred by the action of streams or in lake bottoms, as in the earlier time of the Orinda Formation. The combination of rocks formed during the million-year period of Round Top’s volcanic activity is called the Moraga Formation.

You can see an impressive cross section of the alternating layers of lava and sedimentary rocks of the Moraga Formation on either side of Highway 24 on the eastern side of the Caldecott Tunnel, which passes through the north-south trending range of low mountains defining the eastern boundary of the San Francisco Bay lowland. These layers have been tilted up nearly to the vertical because of the flexing and faulting of the land due to the tectonic pressure of continental collision. (1)

Since its extinction, the Round Top volcano has been tilted over about ninety degrees, along with the rest of the Moraga Formation, and its interior has been exposed by the combined effects of erosion and quarrying. Today, one can walk up to a cross section of a basalt lava feeder tube (exposed by excavation), which was once deep inside the volcanic cone;

Cross-section view of now horizontal Round Top basalt lava tube.

and one can walk into the tilted crater of the volcano to see lithified layered ash and massive basalt.

basalt lava flow, and ash

A video about Round Top, which also shows scenes of the countryside in and about Robert Sibley Volcanic Preserve, is posted on the Internet at

http://youtu.be/ZWk47VrRbKk.

This article is not what the English teachers call a “persuasive essay,” as I have no argument to advance, nor any moral to conclude with. I was just rambling on my own, following trails in my mind. But, I will leave you with this, from one future rock to another: have fun and be kind.

Note

(1) For photos of the road-cut at the Caldecott Tunnel (Moraga Formation), see the following web page (and the web links therein):

The route 24 cut, south side
11 August 2013
http://oaklandgeology.wordpress.com/2013/08/11/the-route-24-cut-south-side/

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Originally published at:

The Volcano Behind Oakland
12 August 2013
http://www.swans.com/library/art19/mgarci69.html

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Mendocino County, 2019

I just came back from a visit to Mendocino County, California, and here are 20 of my pictures from that trip. I’ve chosen to present these photos at a “large” size (not “full”) and “high” resolution (not “maximum). I hope you enjoy them.

We stayed in this house, designed to collect solar heat with its high row of windows facing south, and its full length solarium. The large vegetable and fruit garden is being prepared once again for the coming spring.

 

A meditative spot by the house is the Koi Pond.

 

Daffodils have started to carpet the green fields of the old cemetery for the town of Manchester.

 

Navarro Beach, where the Navarro River meets the Pacific Ocean, south of the hamlets of Albion and Little River.

 

I can never take too many pictures of the beach and surf.

 

The “isness” of nature is so beautiful, it takes you out of yourself and into the universal and primordial.

 

Grace Carpenter Hudson (1865-1937) was an American fine arts painter. She made this self portrait in oil, in 1881, when she was a 16 year old art student in San Francisco. This photo is only of a portion of the full painting.

 

Grace Hudson spent most of her life in the small city of Ukiah (inland Mendocino County), where today many of her art works are displayed at the Grace Hudson Museum.

 

Grace Hudson focused her artistry on the portraiture of the Pomo Indians, who live (still) in the Ukiah and Potter valleys (of inland Mendocino County). She painted real people in the natural settings of the region. This particular painting is about “the birth of song.”

 

A young Pomo girl with her pet fox.

 

A young Pomo girl with an orange, and attitude.

 

Grace Hudson made many paintings of Pomo children and babies. This is a detail of one of her best known “baby pictures.”

 

Grace Hudson sketched this amazingly subtle and detailed portrait of an expert Pomo basket weaver, and friend, with bitumen (which I think of as a coal/tar crayon).

 

Nit’s Cafe is a small, wonderful Thai-themed restaurant in Fort Bragg.

 

This view shows over 90% of the dining area of Nit’s Cafe. Note the potted orchids and colored lights. The food is phenomenal; the seafood is exquisite.

 

Menus at Nit’s Cafe.

 

Here is the chef of this one-woman enterprise, Nit herself: an accomplished gourmet chef who combines refined French culinary technique with Thai sensibility, and a passion for fine cooking. A lively and lovely person. Nit’s is at 322 CA Hwy 1 (the main street through Fort Bragg, in the center of town).

 

Point Navarro, north of Navarro Beach and south of Albion and Little River; looking west toward the setting sun, from near the edge of the high cliff (rocky surf below, and a very windy day).

 

The ceaseless surf at Navarro Point.

 

Looking north from the same cliff-edge spot at Navarro Point.

 

Living in Cadillac Desert

The American West is a land transformed by an immense network of water projects that cannot be indefinitely maintained. When will this land accumulate too many people (and salt) and lose too much water (along with the accompanying salmon and trout) to continue maintaining the present industrialized paradise? Marc Reisner explored this question in depth in his superb book Cadillac Desert. This book reminds me of Thucydides’ History Of The Peloponnesian War because even though Cadillac Desert focuses on the history of water development projects in the American West it reveals the essential (and fatal?) political flaw of the American republic, which is based on the all-too-common human failing of short-sightedness in self-interest.

The following books and videos can help one appreciate the natural history of our Cadillac Desert, and both its allure and potential danger to so many.

Desert Solitaire, A Season In The Wilderness
Edward Abbey
1968

Edward Abbey’s Desert Solitaire is a wry, witty and poetic evocation of life in the high desert, immersed in unbounded nature and remote from civilization. It is as if Abbey had tried to conjure up for himself the sense of John Wesley Powell’s experiences on the Colorado River a century earlier. Beautiful, but I suspect today only an unrepeatable echo of the past.

Cadillac Desert, The American West And Its Disappearing Water
Marc Reisner
1986, revised 1993, Penguin Books
ISBN 978-0-14-017824-1 [paperback]

A masterpiece of Thucydidian timelessness, a tomogram of the American republic taken from the West. Read it [the videos are not enough].

Cadillac Desert
“jkoomjian” states:
Cadillac Desert, Water and the Transformation of Nature (1997), an American four-part documentary series about water, money, politics, and the transformation of nature. The film chronicles the growth of a large community in the western American desert. It brought abundance and the legacy of risk it has created in the United States and abroad. The first three episodes are based on Marc Reisner’s book, Cadillac Desert (1986), that delves into the history of water use and misuse in the American West. It explores the triumph and disaster, heroism and intrigue, and the rivalries and bedfellows that dominate this little-known chapter of American history. The final episode, is drawn from Sandra Postel’s book, Last Oasis, (1992) which examines the global impact of the technologies and policies that came out of America’s manipulation of water, demonstrating how they have created the need for conservation methods that will protect Earth’s water for the next century. This recording [of the series] comes from old VHS tapes, and the quality is messed up in places. But, it is nearly impossible to find copies of the original series anymore. Just a single copy of the first episode is for sale on Amazon, and the guy selling it wants $1000!! Or you can watch it here for free 🙂 [thanks jkoomjian]
Episode 1, Mulholland’s Dream (part 1)
http://www.youtube.com/watch?v=hkbebOhnCjA
All subsequent segments of video for the entire series can be linked from here. Also, all the video sequences are listed at jkoomjian’s video grid at:
http://www.youtube.com/user/jkoomjian/videos?view=0&flow=grid
Episode 1 is divided into 9 segments of 8 to 10 minutes (90 minutes).
Episode 2, An American Nile (in 6 segments, 1 hour)
Episode 3, The Mercy Of Nature (in 6 segments, 1 hour)
Episode 4, Last Oasis (in 6 segments, 1 hour).

Introduction To Water In California
(California Natural History Guides, 76)
David Carle
2004, University Of California Press
ISBN 0-520-24086-3 [paperback]

All the details about the water systems of California, from the mountains (Nature) to the taps and irrigation pipes (Man).

The Making Of A Continent
text and photographs by Ron Redfern
1983, Times Books
ISBN 0-8129-1617-4 [big beautiful paperback]

Ron Redfern used photography to tell the story of the geologic history of the North American continent. His book accompanies a six-part series of one-hour television programs broadcast in 1986 [I think expanded from a 3-part series with episodes 4, 5 and 6 from 1983]. I was fortunate to make VHS copies from TV broadcasts received with an aerial in 1987 and 1988, which I would aim just so for best reception, that requiring I climb onto the roof of my house repeatedly to aim the antenna before each broadcast. This is my favorite TV series, of which episode 4, “Corridors of Time” is my favorite hour of television. The photography, graphics and narration of the video series are all fascinating. Ron Redfern’s text in his book is very good also, informative and engaging. Episode 2, “The Rich High Desert,” describes the Ice Ages and shows some of the geologic and climate history related to Marc Reisner’s Cadillac Desert, and Episode 4, “Corridors of Time” is about the Grand Canyon and the Colorado River, whose shameless exploitation for irrigation Reisner recounts in detail. One source for the video series, on DVD, is shown next.

The Making Of A Continent
The complete 1983 BBC/WTTV Chicago co-production chronicling the birth and development of the North American continent. All six hour-long episodes are packed into 2 dual layer All Regions DVDs.
VOLUME 1
Epi. 1: Collision Course | Epi. 2: Rich High Desert | Epi. 3: The Great River
VOLUME 2
Epi. 4: Corridors of Time | Epi. 5: Land of the Sleeping Mountains | Epi. 6: Price of Gold
http://www.mediaoutlet.com/the-making-of-a-continent-dvd-set-complete-tv-series-2-discs-p-1043.html

Episode 6 of The Making Of A Continent is about California, and the following items all describe features of the state (also note Introduction To Water In California, above).

Faulting California
“Jere Lipps of the UC Museum of Paleontology & Integrative Biology at UC Berkeley explores California’s enormous diversity of geology, landforms, and biology which has been shaped by more than 200 million years of seismic activity. Series: “Uniqueness of California” [9/2005] [Science] [Show ID: 9522]” A one hour lecture (narration accompanying still and video visuals) from 2005, mainly about the San Andreas and Hayward and Calavaras fault systems, both their formation and present dangers.
http://www.youtube.com/watch?v=QzdBx9zL0ZY

A Dangerous Place: California’s Unsettling Fate
Marc Reisner
2003, Penguin Books
ISBN-13: 978-0142003831

Peggy Vincent writes (on December 14, 2003, link below): “Marc Reisner’s last book, dammit. What a great guy Marc Reisner was. He wrote A Dangerous Place: California’s Unsettling Fate as he was dying of cancer, and it’s not just a benchmark of California’s environmental history but also a profound and emotional valedictory effort. Living as I do within ¼ mile of the grumbling and growling Hayward Fault, I found Reisner’s projections of the cataclysmic effects of the Big One to be more than unsettling. Those of us who are priviledged or doomed to live in this glorious state cannot fail to take heed of the picture he paints of the likely events surrounding our upcoming tectonic hiccups, belches, and sneezes. The book is divided into 3 sections. The first retells California’s environmental history from the era of Junipero Serra’s mission system right up to our own freeway system. The middle section deals with the fundamentals of plate tectonics. But it’s that 3rd section that looks forward to (shudder) a hypothetical eruption of the Hayward Fault in 2005 that is most gripping. Yikes. Sayonara to a great environmentalist and author.”
http://www.amazon.com/Dangerous-Place-Californias-Unsettling-Fate/dp/0142003832

“A Dangerous Place” by Marc Reisner [Salon book review]
Katharine Mieszkowski
5 March 2003
“Plunged into the Bay? Smothered in the superstore? Californians may have forgotten about their looming apocalypse, but eco-journalist Marc Reisner’s final work is here to remind them.”
http://www.salon.com/2003/03/05/reisner/

Geologic History Of Middle California
(California Natural History Guides: 43)
Arthur D. Howard
1979, University Of California Press
ISBN 0-520-03874-6

Arthur D. Howard’s little book on the geologic history of California from King City to Point Arena from the Pacific Ocean to the Sierra Nevada Mountains is now out of print, replaced by Doris Sloan’s 2006 book (following). However, though more recent work has made some of Howard’s dating and sequencing of events a bit less accurate, his effort to give one fluid pocket-book sized narrative of 230 million years of California’s geologic history, for a popular readership, a noble and very engaging work. His numerous pen-and-ink (and watercolor) illustrations and perspective cutaway diagrams, especially his incredibly detailed, scaled high-altitude view of the entire territory under consideration (Figure 1, Physiographic diagram of Middle California) are just endlessly fascinating. The sixteen photographs of geologic features are all interesting and beautiful. I wish this book had been revised for greater technical accuracy given present knowledge, but with as few other changes as possible. It was a gem.

Geology Of The San Francisco Bay Region
(California Natural History Guides, 79)
Doris Sloan
2006, University Of California Press
ISBN-13: 978-0-520-24126-8

Doris Sloan’s book is a fat pocket-book, encyclopedic, profusely illustrated, describing the San Francisco Bay Area from Gilroy to Gualala from the Pacific Ocean up to the Central Valley, taken as seven regions (Marin County; San Francisco; The Bay and The Islands; The Penninsula: Coast, Redwoods and Bay; The South Bay; The North Bay; The East Bay). Detailed descriptions (and illustrations) are given for numerous locations within each of the seven regions. This book is a vast collection of detail logically organized and tightly packed. It is ideal as a guide book for visits to many points of geological and naturalist interest in the San Francisco Bay Area.

Roadside Geology Of Northern California
David D. Alt and Donald W. Hyndman
1975, Mountain Press Publishing Company (Missoula, Montana)

Alt and Hyndman’s book is a guide to the geology that you can see while traveling along California’s highways. The book divides the territory under consideration (north of San Francisco) into four regions: the Coast Ranges, the Sierra Nevada and Klamath mountains, the Great Valley, and the Cascades and Modoc Plateau (volcanic). The geology along highways running through these regions is then described in some detail with text, diagrams and photographs. This is a nice book to have as a passenger on a roadtrip in Northern California.

California is a modern paradise of uncertain water supply and shaky ground. Our best collective survival here must depend on a wider sense of appreciation of the land and each other.