Hastings Geology

The work of Dr. William R. Dickinson

Dr. William R. Dickinson, a retired professor of geology at Stanford University, visited Hastings in April of 1972. Hiking with Dr. Jim Griffin, Dr. Dickinson created a map based on the latest USGS 7.5′ quad map at that time. What follows is a summary of his notes on the map and contents of a letter of August, 2000. To summarize the map, Tv = Volcanics of Red Hill, Big Creek Canyon, Buckeye Hill, and School Hill. Volcanics are underlain by thin sandstone wedges, as on Buckeye Hill, but mainly rest on granite and overlain by main Miocene sedimentary section in trough of syncline. Qls = landslides of volcanics.

Dr. Dickenson’s map

These landslide are typical rotational slips where steep hills simply rotate, leaving a cup-shape above a level shelf. The level shelf surface is the former hillside. Two large examples are present on Red Hill (see map), and a small rotational slip occurred on the south side of Red Hill during the El Nino winter of 1998. Clear faults occur in section 5 diagonally through section 9. This fault line extends down the Carmel Valley, revealed by a series of “sag ponds”, the largest of which is Tularcitos Pond, and include Laguna Conejo. These ponds occur in a conspicuous line from Hastings, through Oak Ridge Ranch, Rana Creek Ranch, Rancho Tularcitos and Carmel Ranch Company. Granite side of the contact between volcanics or sedimentaries and granite is indicated by a long line with crosshatching.

Although no other geological map known to Dr. Dickinson in August of 2002 shows the kind of detail for Hastings, there are three Stanford University theses done under his supervision that discuss the geology up and down Carmel Valley from below the San Carlos Ranch up past Hastings. All are available a the Branner Geological Library at Stanford, and all contain geological maps of the relevant area at 1:24,000.

They are:

Brown, E. H. 1962. Geology of the Rancho San Carlos area, Monterey County, California (Student M.S. Report): Stanford University, Stanford, Calif., 56 pp.
Neel, T. R. 1963. Geology of the lower Tularcitos Creek-Cachagua Grade area. Jamesburg Quadrangle, California [M.S. Thesis]: Stanford University, Stanford, Calif., 72 pp.
Weidmann, J. P. 1964. Geology of the upper Tularcitos Creek-Cachagua Grade area.Jamesburg Quadrangle, California [M.S. Thesis]: Stanford University, Stanford, Calif., 74 pp.