Dewitt Canyon Geology
Dewitt Canyon nearly bisects the Pico Anticline. About 600 feet wide strip of the (late Miocene) Modelo Formation (yellow in the below geologic map) is exposed in the canyon. This is in the axis of the anticline. Like the other canyons, the Towsley Formation (early Pliocene) and the Pico Formation (late Pliocene) are also exposed.
The seven older wells were drilled in the Modelo Formation. The four later wells were drilled in the newer Towsley Formation.
Here is a geologic map of the Towsley and Wiley Canyon area from Winterer and Durham (1962). The axis of the Pico Anticline contains the Modelo Formation, which has a yellow color. A small strip of Modelo runs through Dewitt Canyon.
The formation symbols are, from newest to oldest, QTs = Saugus Formation, Tpc Tps Tp = Pico Formation, Tt Ttc Tts = Towsley Formation, Tm = Modelo Formation.
These north flank beds up the east fork of Dewitt Canyon look a lot like some beds in Pico Canyon
Narrow north flank beds in the creek bed of the east fork
These nearly horizontal shale beds are in the west fork close to the well sites showing that we are at the axis of the anticline
The west fork has better exposures of the anticline like these north flank beds
The west fork also exposes these overturned beds of the north flank of the anticline. These beds may be the same overturned beds that are in Pico Canyon (see the geology of Pico Canyon web page)
More beds exposed in the west fork