Geoheritage sites

13 May 2024

My book Deep Oakland: How Geology Shaped a City was released last year on 2 May, so last week marked its anniversary. One reason I wrote it was the one that underlies this blog — to help us more deeply love the ground we stand upon. In the preface I said, “It has features its managers might better heed and others its residents might treasure.”

In my mind Deep Oakland lives in a segment of geoscience called geoheritage, the geological side of a place’s natural and cultural heritage. Geoheritage has its own journal. It also includes a worldwide movement, sadly ignored in this country, that creates formal geoparks under UNESCO. I’ve established a new “geoheritage” category for blog posts that occupy this territory.

With that, let me tell you what I did last week.

Back in 2005, I took part in a memorable field trip to Ward Creek, a Sonoma County locality in the hills above Guerneville that has produced important science since the early 1960s. The local authority who led the trip, Rolfe Erickson of Sonoma State University, said about this spot, “Possibly the most intensely studied body of metamorphic rocks in the world, Ward Creek’s small outcrop is the American standard for glaucophane-bearing metamorphic rocks.” (Glaucophane is the blue-green mineral that lends its color to Oakland’s blueschist.) Ward Creek, in brief, is a prime site of scientific geoheritage, not just a locality of interest but a place of pilgrimage.

However, in the years since 2005 the landowner at that locality has moved on and Rolfe has died. Access to private land can be lost when the human contacts that maintain it are broken. To regain it, the process must be restarted. Some landowners can be beguiled and some reach out on their own; others can never be persuaded.

Recently a new spot on Ward Creek, a few hundred meters downstream, was tentatively opened. The landowner was curious enough to seek a geologist’s insight, and a friendly reconnaissance visit was arranged. I was lucky last week to join that small party of geologists. I brought along three stones I’d collected in 2005 and returned them to their home, close to where I had interrupted their motion downstream.

But that was just a personal, private accomplishment. The overriding goal of the gathering was to see if the site was worthy and to cement warm ties with the owner family sufficient for them to keep welcoming visitors. The visiting party included a veteran field researcher, faculty members from a local college, and a representative of a local geological society, all of us with the same shared goal for our different purposes.

Everyone said the right things, and the site was worthy. It had scenery:

a variety of exotic rock types:

lots of well-exposed bedrock worth mapping in detail:

and plenty of awe inspiration for student and pro alike:

I have high hopes that in the future, well-regulated groups of visitors can experience this place.

An important part of geology isn’t taught in textbooks: the care and feeding of relationships. There are specific bonds between teachers and students, among professionals, between author and reader, between speaker and audience, between masters of past times and moderns who surpass them. I’ve witnessed these many times over the years, but it was a first for me to see links being made between people with different interests in the same precious land — the basic bond of geoheritage.

Oakland, too, has some exceptional localities for geologists and geologizers on the public lands in and around town. They’re the basics of our own geoheritage, and we’re lucky to have them.

Posted in Geoheritage, Outside Oakland | Leave a Comment »

A walk in Oakland’s original platform

29 April 2024

I was asked to lead a walk in the old part of Oakland for a group of engineering geologists that ends at a brewpub. The 3.8-mile route I chose feels too good to keep private. It’s as much about interesting parts of town as about interesting bits of geology.

Here’s how it relates to the geologic map.

Start down by Heinold’s near the wolf, in Jack London Square.

Admire the fountain, check the nearby bathroom, then head along the shore, past the pavement, to the point where Lake Merritt Channel reaches the Estuary. Admire the hills running from here to Mission Peak, down the waterway in Fremont. This is the shape of the East Bay: a row of high hills, a level plain, a wide bay.

The channel, once upon a time, separated the villages of Oakland and San Antonio (later named Brooklyn). Boats were the usual way between the towns — Oakland the squatter village of farm estates wrangling with Don Vicente Peralta over ownership of his ranch land, San Antonio the older shipping depot for Don Antonio Peralta’s ranch and the farms of his peaceable neighbors.

Turn hillward and take Oak Street, then Fallon Street to the Oakland Museum of California. The whole walk so far, the last mile and a half, skirts the edge of the natural platform that made Oakland such an attractive site for developers. The sunken museum entrance on 10th Street is right on the line between this platform, made of windblown sand dunes that accumulated during the latest ice age, and old wetlands that have been filled in since 1850. The dunefield slopes up to the left and the filled land still lies low.


View down 10th Street past the museum on the left

Enter the museum and walk through to the public garden, a good place to sit or use the museum’s bathrooms. Along the way, say hi to J. B. Blunk’s redwood sculpture “The Planet.”

In the garden, notice how the museum works with the natural slope.

Exit the far side and cross the busy 12th Street causeway to Lake Merritt. Here’s where to study the hills and perceive the level landforms around the lake that formed at different times in the latest ice age. (I’ve made an annotated panorama of just this view.) After that, walk up onto the dune platform, by crossing the lawn next to the Camron-Stanford House, and go left a block to 13th Street. From there to City Hall is about a mile passing by some major buildings old and new.

At City Hall, inspect the moat around the building, which is part of its base-isolation retrofit after the 1989 earthquake. This landmark piece of seismic engineering is in all the textbooks. (A similar system was recorded in action during the recent Taiwan earthquake; the video is on Xitter.)

The last mile winds through picturesque parts of old Oakland. One notable building is the Wilcox Block on Broadway at 9th Street, our oldest commercial structure. It survived the great earthquake of 1868, the year it was built, without significant damage, as well as 1906 and 1989.

The route ends in the middle of a tempting set of brewpubs that have made the old Warehouse District a beer fan’s destination. Which to choose is an exercise left for the reader.

Posted in Oakland geology walks | 2 Comments »

Further earthquake reading: Philip Fradkin

15 April 2024

Lately I’ve been going through my bookshelf and revisiting some memorable titles by and about geology, from the 1830s to today. Today I want to share three standout books of particular relevance to Oakland readers, all by the late Philip L. Fradkin (1935-2012). They constitute his “earthquake trilogy,” published between 1998 and 2005. They all concern our particular place between the Pacific and North America plates. They’ve stuck in my mind for decades and still inform my approach in this blog.

Fradkin offered this explanation of the trilogy on his former website:

As a journalist and resident of California since 1960, I am quite familiar with disasters, having observed all types and having been a victim of fires and floods. I wrote in The Seven States of California that there were three ways to deal with such disasters: leave the state, take up religion, or live one day at a time, the last being my personal preference.

So I set out to explore the splitting of the earth’s crust, my designated batter for exploring the effect of nature on humans, first in a general overview and California-centered book, Magnitude 8, then in a wilderness setting, Wildest Alaska, and finally in an urban setting, The Great Earthquake and Firestorms of 1906. In this manner my Earthquake Trilogy unfolded.

As he hints, his treatment goes beyond mere earthquakes to explore the ways we carry on our lives on a planet capable of dealing us death and wholesale destruction. What follows is based on reviews I wrote long ago somewhere else. Both the books (all still in print) and the reviews have held up well.


Palm oases mark the San Andreas fault trace near Indio.

Magnitude 8: Earthquakes and Life along the San Andreas Fault sets the gold standard for treatments of California’s seismic side: the geology, geography, history and political significance of our earthquakes. Fradkin presents not just the familiar cautionary facts and arguments, but also the peculiar sardonic attraction of California’s all-but-official state hazard and the effect of earthquakes on its landscape and inhabitants. He visits the fault’s full length, from Shelter Cove to Bombay Beach and beyond. Like me, he’s more curious about the fault than fearful of it, while aware of its constant threat. He was the same kind of day-at-a-time Californian as me, although I unlike him would not build my house practically upon it.

My review


Phil Stoffer stands by the creeping San Andreas fault near San Juan Bautista.

Wildest Alaska: Journeys of Great Peril in Lituya Bay explores the relations between landscape and culture in America’s most dangerous locality. Fradkin called this his most personal book. Lituya Bay is a rugged fjord in remote southeastern Alaska crossed by the Fairweather fault, whose frequent earthquakes launch huge masses of glacier ice and rockslides into the water causing colossal tsunamis. The bay’s entrance on the stormy Gulf of Alaska, barred by a glacial moraine, is navigable for only minutes at slack water in good weather. Nature looms there, and the human presence is precarious. Even the book’s geologists feel the chill along the spine, and the ghosts of the bay, witnesses to repeated catastrophe since ancient times, reach surprisingly far into our world. Fradkin went there “to explore the dread,” my phrase in Deep Oakland. I too have visited Lituya Bay, and our cold Pacific fog reminds me, like him, of that perilous place. The great natural forces so heightened there are great here, too. Our local libraries do not have this title, but it’s precious to me.

My review


In 1906 the San Andreas fault ruptured here, near Fort Ross.

The Great Earthquake and Firestorms of 1906: How San Francisco Nearly Destroyed Itself is a sweeping, definitive survey of the iconic American urban disaster that delves into how the city’s movers and shakers responded. As Fradkin’s publisher put it, “after the shaking stopped, humans, not the forces of nature, nearly destroyed San Francisco in a remarkable display of simple ineptitude and power politics.” The aftermath is the subject that scares me the most when I think about the Hayward fault, and there are important lessons for Oaklanders at all levels of citizenship. Both in 1906 and after hurricane Katrina in 2005, the bedrock of human nature fractured in very similar ways. What happened there will happen here some day. Fradkin’s journalistic presentation of original material brings the great quake to life from beyond the veil. He has the best stories, including many no one else has found. The Internet Archive maintains a copy.

My review

A theme that crosses all three books, one I barely touch on in my own Deep Oakland, is that while we can venture into wild nature expecting its dangers and tasting its corresponding thrills, wild nature is just as capable of visiting its dangers on us at home. Earth and civilization are not separate things, and both are prone to break along known fractures. These are books to study when you’re ready for the next level.

Posted in Earthquakes | Leave a Comment »

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