When presented with the topic of plant fossils, I honestly wondered if I had the qualifications, even as an intern, to work on something so important. Especially such a rare find - out of Box Springs, no less. But as it goes, I had come to learn - and the learning began almost immediately.
The fossils consist of one sycamore leaf, a willow leaf, and scrub oak. They are embedded in sandstone, which is all the more baffling - not only are plant fossils a rare enough find, but Box Springs is mostly granite. To have been preserved the way they are, it would have had to have been instant burial. In addition, having been found in a lower area between two hills (where the road was built), it's a relatively safe assumption that because no other sandstone was found in the area besides one seemingly unrelated piece further up the hills, this particular portion of rock was only formed in a small pocket in that one location.
The florule fossils found are stream plants, and having been there now I can say with absolute certainty I can't even imagine a stream running through there. It is absolutely barren, desolate, and extremely hot. These plants, which require lots of water and less arid conditions, are a clear sign that things were not always the way they are now. They're likely to be Pleistocene, as conditions during that time allowed flora such as the evergreen scrub oaks to flourish at lower altitudes, such as the Box Springs hills in the late glacial period. The scrub oak fossil is found where only coastal sage shrub grows now (which is deciduous and goes dormant during drought months), giving a clear visual into a time when water was more abundant in the area. Scrub oak has been recorded to have been at lower altitudes during the late glacial period, as well as many other plants that now only live at higher, cooler altitudes.
Although it seems clear that the fossils should date to be Pleistocene, should they be found to be Holocene, we will have quite the mystery on our hands. They have yet to be dated. For now, though, they fit right into what we know about the last glacial maximum in southern California. This, of course, does not make them any less of a significant find - it only strengthens what we know, and it's extremely exciting.
As for the project, this is where we're beginning. In order to assess the Box Springs plant fossils properly, it's important to put them into context with the rest of what we know about paleoflora in the Pleistocene. That being said, I'm going to be researching climate conditions and the effect on plant growth during the Pleistocene and putting it together to build a background around the plant fossils we found.
In addition, as a more personal approach to the topic, I'm hoping to also look into possible causes for the burial event. Finding sandstone in a pocket such as that in an otherwise granitic landscape is interesting - although the event was likely a flash flood, possibly by thunderstorm (as Rich suggested), I'm still curious to look into the area more and see if it's possible to find anything else that might give us a clue on the geological processes that might have contributed to the fossil's formation and preservation.