Because I walk through the area regularly, I’ve kept an envious eye on the excavation at the southeast corner of 27th Street and Broadway. Since the building slated for the site doesn’t have a name yet, I’ll call it the Biff’s site after the much-loved but long-departed Biff’s Coffee Shop that once sat there. It’s at the center of the maps below — first the Google terrain map.
Then the historic map. This is from an 1888 map compiled by state surveyor Julius Henkenius, served up by the David Rumsey Map Collection. What I like about it is that it shows the creeks. The main stream is Glen Echo Creek, with the Broadway Branch joining it near the top of the map.
The 27th and Broadway site appears to include the southern half of the Cogswell tract, presumably the remarkable Henry Cogswell whose great monument is a highlight of Mountain View Cemetery.
Anyway, what’s under the ground here? For that, we want the geologic map. This site is at an interesting intersection.
The site is flanked by two lobes of the ancient alluvial fan (Qpaf) that covers central Oakland. The one on the left is Pill Hill — which was known as Academy Hill in the 1880s and the site of Anthony Chabot’s first municipal reservoir — and the lobe on the right is Adams Point Hill. To the south, the ground is mapped as Pleistocene marine terrace deposits (Qmt), and the site itself is mapped as ordinary alluvial sediment.
Knowing all that, it would have been fun to poke around as the excavation proceeded from 24 March . . .
. . . to 1 April . . .
. . . to 19 April . . .
. . . to 7 May, when the digging was complete and the foundation prep was under way.
The chances were that no mammoth skulls or other cool megafossils were present, but you never know. It all looked like well-sorted fine sand from my distant viewpoint, what you’d expect. If this had been a Caltrans project, they might have retained a paleo firm to watch the digging and grab any fossils the dozers turned up. But as of last week the exposure is all over.
Most of the time, science is just an indulgence. But as Oakland enters a downtown building boom, it would be nice if the experts got a chance to document and sample some of these big holes.
Oakland Geology 
25 June 2017 at 11:06 am
I also walk by this site on my way to the Y. Fossils may not have been present but there was a good chance Native American artifact may have been unearthed.
15 June 2017 at 10:59 pm
At 17th and Broadway, the foundations of a former post office, huge chunks of brick, showed up when they excavated. And I heard that human bones turned up in a test drill along Webster. Jimmy Hoffa?
28 May 2017 at 6:51 pm
I too am amazed at how much building is going on in Oakland. But until reading your post it didn’t occur to me to also see this as an opportunity to investigate the geology and paleontology of our town. A sadly ignored opportunity.
22 May 2017 at 2:05 pm
Thank you for documenting this site. I, too, walk through the area often, and I would love to see a little anthropological curiosity about what the site had held before the earth was hauled away.
I really enjoy your posts.