Avalon Hill

There’s a little hill south of the UC Berkeley campus, near the Claremont Resort and the Hayward fault, that cried out for a visit. It stands out on Google Maps (with the “terrain” setting, naturally).

On the geologic map, it appears as a blob of Franciscan sandstone.

I thought I’d give it the same treatment I gave Easter Hill in Richmond: explore the rock and comb through old maps and documents.

The road running by the south side of the hill is Avalon Avenue, so I’ll call it Avalon Hill. It was never exactly a landmark, but it has a past and retains a certain presence.

The hill was owned by John Kelsey in the late 1870s, and Kelsey Street commemorates his name. Today’s Claremont Avenue was called Telegraph Avenue at the time, as shown in the 1878 Thompson map.

In 1884 the Berkeley Water Works excavated a large reservoir on the hill, and the following year the Alameda Water Company took it over. The Garber Reservoir held a million gallons and was lined with concrete. Here it is on the 1894 Wagner map.

It is not to be confused with today’s Garber Reservoir, the flat-roofed structure 1500 feet south on the north side of Claremont Avenue.

Development began to surround the hill in the 1890s and 1900s, especially after the 1906 earthquake. From then until the 1930s, the struggling private water companies of the northern East Bay merged, the East Bay Municipal Utility District swallowed them whole, and the water delivery system began a slow and expensive transition to the rational and robust setup we enjoy today. The 1912 street map shows the property still in the hands of the Peoples Water Company, the next-to-last of the private firms.

I don’t know when the reservoir was decommissioned and removed, but the homes adjoining it were built starting in the 1910s. The large home on the hilltop was apparently built in 1960.

The best picture of the hill itself is the digital elevation model made from a special survey of the Hayward fault. Its sides are too steep for streets, which has helped keep it quiet and isolated.

On the north side, Garber Street has a rustic interlude where a narrow road sashays down the hillside like a mini-Lombard Street. Avalon Avenue, on the south side, is blessed with three stairways, one at the end and two going down to Russell Street.

All those old houses with their mature landscaping cover up the rocks very effectively, I can testify. But there’s an excellent exposure at the end of Avalon Avenue underneath a private driveway.

What few flat surfaces there are on it appear to reflect fracture planes, imposed by the tectonic stresses on the rocks over the years, rather than any original bedding.

Up close, the rock is a hard siltstone much like the rocks in the quarries of the Piedmont crustal block: the Bilger, Blair and Davie tennis stadium quarries.

But just looking at it isn’t definitive. The geologists who’ve mapped it have left it unclassified (KJfs) rather than lumping it with the sandstone of the Novato Quarry Terrane (Kfn) exposed in the Piedmont block to its south. Here’s a larger piece of the geologic map showing what I mean: it might be the northern tip of the block or it might be the first of a string of rock bodies to its north. The thrust fault leading up to it, the dotted line with the teeth on the upthrown side, is reasonable but conjectural.

Avalon Hill is a cool little bit of Berkeley. Stick your nose in and poke around some time.

Yes, “Avalon Hill” is a private joke. My siblings and I warped our personalities in the 1960s by moving armies and fighting over the rules of the board-based wargames produced by the Avalon Hill company, starting with Tactics II and Gettysburg.

2 Responses to “Avalon Hill”

  1. mpetrof Says:

    We always called it the Garber Tract. There was a Judge Garber around the time it was developed. It is probably the most expensive neighborhood in Berkeley. It has views, privacy, proximity and large to very large homes.
    I appreciate your speculation about the rock type. I guess that thin sections and other analysis could nail it down tighter but being reminded of the provisional nature of much geology is also appreciated.

  2. Neal Parish Says:

    This post is cool — I live right behind the Claremont Hotel, and often walk down or up Avalon or Garber.


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