The middle Miocene earth was a warm place. Warmer than today’s average temps (though, with climate change, we are getting there). The Arctic ice cap likely did not exist. Antarctica was only partially glaciated. Mountain glaciers were rare. Too, California was lower than today. All of this made for a much higher sea level. As you can see, there are a lot of versions of what the California Miocene looked like. There are more I’m sure. I started at the simple with View 1. View 4 is from Ronald Blakey’s website. His maps seem to be the most popular on the net (but I’m not sure if they are the most accurate). View 5 is a map that my brother, Rod, generously made for me. I tried to follow some others a bit but included my own ideas as well. That doesn’t mean that I think my map is the most accurate though. View 6 is from Clarence Hall’s Marine Nearshore Paleoclimate Regions which is generally considered to be accurate. Still, I envision the Temblor Sea (the inland body of water) as bigger.
The Temblor sea figures large in Opalescence. Why not go for a stroll down its pristine banks?