Archive for July, 2011

Grizzly Peak and Moraga basalt

25 July 2011

In northernmost Oakland is the small, steep Panoramic neighborhood, which perches on the high ridge between Strawberry and Claremont canyons. At the top of Panoramic Way is this view north across Strawberry Canyon to Grizzly Peak, which at 536 meters (1758 ft) is the highest point in Oakland. Click the photo for a 1000-pixel version.

grizzly peak

The bottom of the photo grazes the UC Botanical Gardens. The lowest slopes in this view are underlain by the Claremont chert, up to the powerline tower directly below the peak. Above that is the Orinda Formation, and the ridgeline is lava of the Moraga Formation.

To the right of the peak, on this side of Grizzly Peak Boulevard, is a big, towering outcrop of basaltic lava; here’s a closeup.

basalt

That seems like it would be worth a visit, if the poison oak isn’t too bad.

Joseph Le Conte’s grave

17 July 2011

Joseph Le Conte (1823–1901) is probably the most eminent geologist in Mountain View Cemetery. Born in Georgia to a wealthy family, he graduated from the University of Georgia in 1841 and earned an M.D. in New York in 1845. Five years later he gave up his practice in Macon to study geology and zoology at Harvard under Louis Agassiz, earning a B.S. in 1851. He then taught geology at three different universities, then endured the Civil War on the losing side, before riding the transcontinental railroad to Oakland in 1869, where he became the first professor of geology at UC Berkeley and his brother John the acting president, later a professor of physics. He spent the rest of his life here. The Cal paleo museum has a page about his role during this time. A much longer memoir, by Cal botanist Eugene Hilgard, was published by the National Academy of Sciences in 1907 and is fascinating reading.

In 1870 he first visited the Sierra Nevada, a six-week excursion on horseback, and traveled the West extensively thereafter. He moved with his family to Berkeley in 1874; “He always greatly admired and enjoyed the site of the university and town,” Hilgard says. The next year he was elected to the National Academy of Sciences. Le Conte’s textbook Elements of Geology was published in 1878 and went through four editions before his death. He was a dedicated and brilliant teacher who once said, “We never know any subject perfectly until we teach it.” As a writer, I can relate to that.

He died of heart failure in his beloved Yosemite Valley, which he was showing to his eldest daughter, on 6 July 1901. The funeral was a week later. “Many came from long distances to pay this last tribute of respect to Joseph Le Conte; the regents, faculties, and students of the university, where all activities had been suspended for the day, and a long line of carriages formed an imposing procession, accompanying the body to Mountain View Cemetery, near Oakland, where it was interred alongside of his brother John. A few months later the grave was marked with a large granite boulder procured by the Sierra Club from the vicinity of the camp where he died, in the Yosemite Valley.” So the “Yosemite” engraved on the stone must refer to the place where he died. Among his achievements, Le Conte was a founder of the Sierra Club.

Hilgard wrote of him, “It was Le Conte who through whom the University of California first became known to the outside world as a school and center of science on the western border of the continent; and for a number of years he almost alone kept it in view of the world of science. His presence and connection with the University was largely instrumental in attracting to it other men who otherwise would have hesitated to emigrate from their eastern homes to what was then the outskirts of civilization; and his ceaseless scientific activity acted as a strong stimulus both to his colleagues and to the students coming under his instruction, whose affection and esteem remained with him through life. . . . His modesty and simplicity survived, unscathed, the applause and laudations bestowed upon him, and his strong will and cheerful disposition carried him up to a mature age in undiminished mental vigor, despite an apparently frail body.”

Oakland stone landmarks: Middle Harbor Park’s replica training wall

5 July 2011

Even before I knew what it really was, this short pier at Middle Harbor Park stood out.

middle harbor pier

This is clearly not a typical groin or breakwater, something that is dumped into place, but a carefully laid work of drystone masonry. It feels absolutely solid to walk upon. And then there are the rocks in it, a rich assortment of large and pristine Bay area specimens. There are tuffs composed of volcanic pyroclastic flows,

tuff

colorfully metamorphosed volcanics,

metatuff

slickensided serpentinites,

serpentinite

and other metamorphics whose colors could inspire a fabric maker.

jacob's coat

Also sandstones and even a few ringers of Sierran granitic rocks, perhaps from the old quarries of the Rocklin area. But it’s not typical of a modern marine rockwork—those use stone trucked in from a single quarry to save money and control the quality.

An interpretive sign explains that it’s a replica of the old “training wall” on the north side of the shipping lane to Oakland Inner Harbor, where the signature gantries load and unload big freighters. Training walls are jetties designed to turn a shipping channel into a flume during ebb tide, keeping the bottom clear of mud. The walls were built around the 1880s, using shoreline quarries around the Bay and shipping the rock here by barge. That explains the unique variety and distinctive regionality of the material.

The north training wall was removed when the shipping lane was enlarged in 2001, but they saved some of the stones. Masons installed them over a core of rubble, and here they are. The south training wall remains in place.


Follow

Get every new post delivered to your Inbox.

Join 4,029 other followers