The purpose of this road log is to provide information on the location of significant stratigraphic horizons within the Monterey Formation along the coastline west of the city of Santa Barbara. Particular emphasis is placed on the location of the Luisian-Mohnian stage boundary, and the lithostratigraphy of the Luisian and Mohnian Stages. The Luisian-Mohnian boundary is the most abrupt faunal change which occurs in the benthic foraminiferal zonation of the Miocene in California, and it has been located by Echols (this volume) in four of the stratigraphic sections described in this road log. The upper Luisian and lower Mohnian is also of interest, because this is the interval that shows the most dramatic lateral facies changes along the Santa Barbara coastline. Between Gaviota and Naples Beach this interval was deposited on a submarine bank top, and consequently is characterized by an extremely condensed interval or a depositional hiatus represented by a series of phosphatic hardgrounds. In contrast, this interval is represented by a 100-ftthick chert and porcelanite interval in the city of Santa Barbara that was deposited near the axis of a depositional basin (see the overview at the beginning of this volume).

The road log starts on Highway 101 at the turnoff for Gaviota Beach State Park. Gaviota is located 30 miles west of the city of Santa Barbara and 43 miles south of the city of Santa Maria. The mileage that is listed for each stop is for southbound traffic on Highway 101, starting at the turnoff for Gaviota Beach State Park. References cited in the road log are found in the overview at the beginning of this volume.