Charting The Rocks

Last week’s trip to Bodega Bay afforded me the chance to start doing some geologizing, namely looking at geologic maps for the route from Davis to Bodega Bay. I didn’t have a chance to seek out paper maps (a good index to California geologic maps being here), but did find a couple digital maps, portions of which I printed out. So I am now much more keenly aware of the Sonoma Volcanics (exposed in bits off of Highway 12 on the way to Napa), and the geologic formations on the road from Petaluma to Bodega Bay (which falls on a very recently produced digital map). The break indicated on the map between the late Tertiary Wilson Grove formation (the hills surrounding Valley Ford) and the graywacke of the Franciscan complex to the west just before entering Bodega Bay was quite enlightening to notice on the ground. Keeping track of geologic formations is a whole new way to travel! So off I go to find more maps.