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Posts treating: "Leona volcanics"

Monday, 29 May 2023

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The El Cerrito rhyolite 

Oakland Geology [2023-05-29 17:01:20]  recommend  recommend this post  (44 visits) info
The hills of Berkeley and El Cerrito contain bodies of volcanic rocks that are incorrectly mapped as the same stuff Oakland has. They’re the two pink patches (and a tiny speck between them) on this part of the geologic map. These rocks are colored pink and labeled “Jsv” on the map, but they are not

Return to Pine Top 

Oakland Geology [2022-04-25 17:01:38]  recommend  recommend this post  (140 visits) info
A brief visit to Mills College for the recent pow wow reminded me of some business — not unfinished business, but rather an inquiry ready to renew. The upper end of the Mills grounds is very different from the lush central campus with its beautiful floodplain setting, and it has the possibilities of bedrock and

The pyrite orebody of Leona Heights 

Oakland Geology [2021-05-10 17:01:34]  recommend  recommend this post  (423 visits) info
Through historical accident (or fate), I’ve been a longtime reader of the late Oakland fiction author Jack Vance. As it happens, Vance was exposed to geology by coursework in mining engineering at UC Berkeley, and one of the most charming and memorable features of his Planet of Adventure series, written in the late 1960s, was

The changing identities of the Leona Quarry 

Oakland Geology [2020-11-09 17:01:51]  recommend  recommend this post  (138 visits) info
Last week I finally gave in and returned to the high hills — for exercise, as permitted by the county health authorities — and couldn’t resist a reconnaissance of the Leona Heights area. It’s Oakland’s boldest and most rugged region. Here it is from Knowland Park, above the zoo. Most Oaklanders may know it, though,

Arroyo Viejito 

Oakland Geology [2020-01-06 17:01:22]  recommend  recommend this post  (120 visits) info
Some of Oakland’s most interesting land is also its most inaccessible; I’m speaking of our streambeds. And on the whole, the largest remaining stretches of wild streambed belong to Arroyo Viejo. Just to orient you, here’s the Arroyo Viejo watershed, as it’s mapped today by the Alameda County Flood Control District. The red stripe, which

Oakland and the Coast Range ophiolite 

Oakland Geology [2019-06-24 18:42:37]  recommend  recommend this post  (90 visits) info
A commenter asked, in connection with a recent post, if I’d written anything about Oakland’s ophiolite. The answer is, not specifically until now. The Coast Range ophiolite (OH-feel-ite) is a string of mostly disconnected outcrops of unusual rocks that extends north almost to Redding and south almost to Point Conception, rather like the way my

Return to Sugarloaf Hill 

Oakland Geology [2019-05-13 17:02:56]  recommend  recommend this post  (587 visits) info
It’s been almost four years since my last visit, and no locality, even the wildest, ever stays the same. Sugarloaf Hill, that iconic bump in the ridges of East Oakland, is one of the city’s wildest places. It helps being part of the Leona Canyon Open Space Reserve, an odd holding of the East Bay

Geology of King Estate Open Space 

Oakland Geology [2019-03-04 17:02:50]  recommend  recommend this post  (584 visits) info
After tramping all over Oakland, I still find its landscape full of uncertainty and mystery. The alluring hills of King Estate Open Space Park have brought me here time and again, sometimes to lead walks, sometimes to just stop and smell the flowers. Last month I came back yet again, this time to look harder

Geranium Place rocks and runoff 

Oakland Geology [2014-07-28 06:08:53]  recommend  recommend this post  (774 visits) info

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Geranium Place occupies a sloping bit of land just north of Horseshoe Creek below Redwood Road. This map shows the location plus the sites of the photos in this post. The bedrock here is mapped as Franciscan melange on the west and the Leona volcanics on the east, the same stuff exposed in the huge
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