My aunt have me a coffee table book a number of years ago called "fossil treasures of the Anza borrego" that is really really good. There is amazing collection of fossils there recording a pretty good chunk of relatively recent geologic time, especially mammals. It's been a long time since I went through it, and it is in storage now but on thing I remember is there is a lot of neat stuff relating to climate and the cutting off of chunks of that area from the sea due to all the tectonics in the area. There are many complex fault blocks associated with the transform faults of the San Andreas system.....the result was changes from open ocean to drying super saline lakes, and rivers like the Colorado being cutoff from any exit to the ocean. That creates major changes and adaptations of the ecological systems. Really neat stuff!