The Old Bilger Quarry
Behind the CVS Pharmacy, you can spy a small pond, no more than 600 feet long and maybe one hundred feet wide. But this urban oasis, fed by the Glen Echo stream, is not the natural pond it appears to be. Humans made this hole in the ground.
Emerging from the water, you can see sandstone meeting a darker material called trap rock, which, when crushed, becomes useful for building roads. That possibility did not escape the early American settlers of Oakland. In 1870, the Oakland Paving Company started mining for rock. Three years later, they opened a rail line from the quarry to a depot that sat a few blocks to the southwest at 41st and Shafter. From there, trains could take it all over the area's railroad system.
The quarry and railroad line ran all the way until 1923, operated for much of that time by the Blake and Bilger Company, which had its headquarters downtown at 14th and Broadway.
After the mine closed down, houses were built around the rail line and the quarry filled up with water, but if you look at aerial photos of Oakland, you can still see the curve of the railroad line from where the rock was mined to where the rock was shipped carved into the modern landscape.