Geoscience Reports 27:3 (Spring 1999).
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EDITOR'S ANGLE

     Once again we are focusing on field localities where teachers can take their students for a very close look at the geology. Outcrops of the melange sequences similar to the one described in "Field Trip East of Cool" occur across central and northern California.
    One locality that is not included in this paper, but should be mentioned, is an outcrop of bedded chert just north of San Francisco. At the north end of the Golden Gate Bridge, on the west side of Interstate 101, is a small park called Battery Spencer. On the north side of the road across from the parking area is a spectacular outcrop of sharply folded (chevron folded), thinly bedded chert. Many geologists believe these cherts were originally siliceous oozes that formed as organisms with structures made from silica (e.g., radiolarians) died and accumulated on the ocean floor. They think that as the tectonic plates came together, the siliceous material was scraped, folded and accreted onto the western edge of the continental U.S. The timing for the emplacement of these beds is fascinating since the material had to be firm enough to retain its bedding features, yet soft enough to fold.
    Such deposits add elements of complexity to flood models. We must address not only the tectonic issues but also the oceanic conditions that might contribute to the deposition and accumulation of these organisms.