For those with limited knowledge, (ahem, mostly everyone, unless you happen to stumble across fossils in your yard and take an interest...) Pleistocene fossils range from 2.5 million to 12,000 years old or so and encompass things that were around along with humans, such as saber toothed cats and mammoths. Those are found throughout San Diego County. I won't get into the names of all the places or deposits, but you can find good information at the Natural History Museum and their website (click the "research" tab), along with a map at the SDSU website linked above. The Pliocene epoch contains fossils that are 5.3 million years old to about 2.5 million or so (pre-man). This is the formation that runs through our backyard, and being in such close proximity to the ocean it makes sense that the formation that San Diego has is a marine deposit. As random luck would have it, Jeremy was digging a hole to plant a shrub when he stumbled upon this:
Next thing you know, we have a group of tiny paleontologists excavating through our yard and tediously trying to free their treasures from the sandstone-cement. We found a serious bed of shells and sand dollars, and when we took them to the Natural History Museum the on-site paleontologist told us that we could possibly find sharks teeth, whale bones, and ancient walrus bones! Apparently what we found is from the more recent Pliocene, roughly 2.5 to 3 million years old. Pretty cool!
It made me realize that we are, all in all, sitting on top of a huge bed of our ancient past. Things like this exist everywhere and random luck sometimes makes it more obvious. All of the soil we sit upon or till is the same soil that has been here since before the dinosaurs and by tectonic upheavals the earth sometimes jumbles up the nice, neat layers of natural sedimentation. It makes you realize how small you really are, what a tiny blip we are on the radar of geologic time. I know this is all stuff we learned in grade school, and so is life. People can tell us something a million times. We can hear it and memorize it and repeat it by heart, but sometimes it is a small thing thrown in your face that really gives you that "aha!" moment, that epiphany. Keep on digging!
(And a few books that look pretty interesting, I've been searching for a good on on local fossils and geology)