I was lucky enough to examine this large specimen of fossil wood that I was told came from the hills of San Leandro.
People have told me about and showed me pieces of fossil wood from the East Bay hills before. I’m no expert on the subject, and I haven’t done a lot of fossil hunting in Oakland. But we have young terrestrial rocks around here in addition to the abundant marine rocks—primarily the Orinda Formation, of Miocene age. I assume this came from there.
People have told me about fossil wood in Wildcat Canyon, but that’s regional park land where collecting is forbidden. This specimen, I was told, was from EBMUD land, where collecting is not expressly forbidden, although I assume that vertebrate fossils (animal bones) are protected. I have purchased an EBMUD permit and have been looking forward to using it for responsible geologizing.
Oakland Geology 
21 April 2021 at 12:13 am
I saw quite a few fossil-like impressions in the sandstone cliffs in Las Trampas – but the part which is accessible from Cull Canyon, Castro Valley. on another note, is there any Purissima Formation here in the East Bay? i think it might be closer to the coast – Sta Cruz to Pt Reyes. I have a cool story about a Purissima Formation fossil of Crepidula princeps – which i showed to a Paleontolgist at UC Berkeley years ago. He got pretty excited about it because it was such a marvelous example.
24 March 2013 at 11:13 am
It is. I visited Las Trampas and wrote about it for KQED back in January.
22 March 2013 at 9:31 pm
The watershed land at Las Trampas accessible from Crow Canyon is spectacular , and worth a trip.