At the Creepy Winery: A Field Trip Along the San Andreas Fault System III

A busy week prevented me from finishing a narrative on our field studies adventure along the San Andreas fault last weekend. Part I discussed active creeping in the town of Hollister, California, while Part II revealed some landscape features along the San Andreas fault south of Hollister near the Gabilan Range. Another stop was to have a look at the DeRose Winery in the hills south of Hollister (a disclosure: we always stop here, but we had a schedule problem last week, so these pictures are from a previous trip. Students: this is what we would have seen!).

The DeRose, under one name or another, is one of the oldest wineries in California, dating back to 1854. It was once called the Cienega Winery because of the nearby marsh that turned out to be a sag pond along the active trace of the San Andreas fault. The foundations on the original building failed for (then) unknown reasons, and the winery was rebuilt in the same location. That building came apart as well, and was again rebuilt in 1948. When the present building began cracking up, investigations by geologists showed that the winery had been constructed on top of an actively creeping section of the San Andreas fault! It has been a field trip destination for generations of geology students since the 1960's.

As can be seen above, the building is being offset, ripping apart along the foundations. The adjacent driveway has been patched numerous times. The most striking feature on the property is a drainage culvert that was apparently built in the late 1800's or early 1900's. It has been offset by around 3 feet in that time.

The USGS has posted an excellent field guide for the Hollister region that has maps and pictures of the winery, and the Hollister neighborhood discussed in part I. The guide is part of the conference publication of a meeting of the National Association of Geoscience Teachers in 2001 concentrating on the Geology and Natural History of the San Francisco Bay Region. The guide is available from the USGS online only, although the Far West Section of the NAGT has paper copies for sale (proceeds support student scholarships).