The La Honda oil field is the largest oil field in the La Honda basin, which is a very structurally complex basin located on the San Francisco Peninsula. The basin is composed of tertiary sediments and volcanics, and is bounded by granitic highs to the north and south, the San Gregorio fault to the west, and the San Andreas fault to the east. The field, discovered in 1955, produces 16-32 degree API oil trapped only at the very top of the structure in Eocene Butano Formation sands. Over 800,000 bbl of oil have been produced on the structure, both from the domal high and a small pool on the faulted west flank. The south area is located on the Haskin Hill anticline, which is a parallel fold to the La Honda flexure. The deepest pool here also is in the Butano sand in a minor fault trap at the anticlinal crest. A pool of 17 degree API oil in the Vaqueros is overlain by shales of the Pliocene Purisima Formation. A third pool in the south area is in the Burns Limestone. This middle Miocene conquinoid limestone also contains 17 degree API oil trapped by the shales of the Pliocene Purisima Formation in an angular unconformity trap. Despite its age, this field retains attractive extension and development locations that should add significant reserves.