What You Missed When You Missed Glenn Lym’s Talk About the Lost Geology of Bernal Heights

Glenn Lym addressed a full house at the Bernal Heights branch of the San Francisco Public Library on Wednesday night. His presentation focused on how San Francisco transformed the hilly native landscape into flat land suitable for development.

Much of the first half hour recapped Glenn’s HERE5 documentary, which was brilliant. But having first seen that the day before, a second pass helped me understand the process better. Here’s the story:

In 1849, very little of San Francisco was flat. Sand dunes over 100 feet high made land passage impractical between “downtown” and the Mission. Millions of cubic yards of material was moved to create the flat center of San Francisco we see today.

One remarkable photo in the slideshow showed picnickers on a peak of Potrero Hill that Glenn said no longer exists; a spot that is now either Franklin Square or the Safeway shopping center (previously the site of Seals Stadium). I think this may have been called Irish Hill, but I’m not sure. (John Blackburn corrects me in the comments; Irish Hill was on the East side of Potrero.)

In the second half, Glenn showed Coast Survey-based CAD reconstructions of the lost peaks of Bernal Heights, though he wasn’t sure when they had been removed.

Harrison Ryker’s 1938 photos showed a peak at the top of Ripley Street, above the intersection with Peralta, which was missing on a later photo:

An older gentleman in the back, attested by others to have lived on Ripley, said the hilltop removal began in 1939, stopped during the war, and resumed afterwards — leaving the block between Peralta, Esmeralda, Franconia and Samoset flat by around 1950. The debris was probably used to fill Isais Creek, with some of it possibly used as ship ballast.

The fourth peak, where the Franconia/Brewster public gardens are today, south of Rutledge, was removed prior to 1938. Some industry, possibly hilltop-removal, was visible in an aerial photo that showed the Maxwell advertisement atop Bernal Hill, which suggests it happened in the mid 1920s.

Glenn referred to historical posts by Burrito Justice and Bernalwood several times in his presentation, with special attention paid to Burrito Justice’s posts on the Valencia Hotel collapse and Serpentinia, and Bernalwood’s epic post on the history of Army Street/Cesar Chavez’s awfulness.

Bernal’s superior seismic safety was discussed in the Q&A after the talk, though I don’t think our chert was specifically credited.

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9 thoughts on “What You Missed When You Missed Glenn Lym’s Talk About the Lost Geology of Bernal Heights

  1. One of the best presentations by the Bernal History Project ever! Glenn and his presentation were stunning. For clarification, Irish Hill is on the east side of Potrero Hill and Third Street and can still be seen in the area east of Illinois between 20th and 22nd. The hill actually was quite large but over time was cut down, as were many other hills in the City, for development reasons. The current plans to redevelop the shipyard area and surrounding facilities will save the hill from being cut down even more. A piece of San Francisco’s geological history will remain thanks to good planning.

  2. It was a great presentation. For some reason I either have narcolepsy or maybe there wasn’t enough oxygen in the room as it was hard for me to stay awake. I regretfully fell asleep a couple times. I’m stating this because I want to make it clear that this was not intentional at all. It was an excellent evening.

  3. The gentleman at the back that night is Bill Cassidy, lifelong resident of Ripley Street and a walking treasure trove of knowledge of Bernal. He did some of the first oral histories on the hill about thirty years ago. We at Bernal History Project can only hope to follow in his footsteps.

  4. Thanks for the good synopsis.

    The picnickers atop The NW peak of Potrero Hill are in the well known etching of the Inner Mission, about the only depiction of Mission Creek from probably the 1850’s. The peak was where Safeways is now in the Potrero Center. And just like there is a chunk of Irish Hill left near the Union Ironworks Illinois bet 20th and 22nd, there is a chunk of that peak on Alameda bet Potrero and Bryant.

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