HR: 1340h
AN: ED43A-0270    [Abstracts]
TI: Analysis of Serpentine Soils in the Presidio of San Francisco, CA
AU: * Matthew, A
EM: amatthew@sfsu.edu
AF: San Francisco State University, Department of Geosciences, San Francisco, CA 94132 United States
AU: Chan, L
AF: Philip and Sala Burton High School, 400 Mansell St., San Francisco, CA 94134 United States
AU: Cheng, J
AF: Balboa High School, 1000 Cayuga Ave., San Francisco, CA 94112 United States
AU: Khalil, M
AF: Philip and Sala Burton High School, 400 Mansell St., San Francisco, CA 94134 United States
AU: White, L D
EM: lwhite@sfsu.edu
AF: San Francisco State University, Department of Geosciences, San Francisco, CA 94132 United States
AU: Gonzales, J
AF: San Francisco State University, Department of Geosciences, San Francisco, CA 94132 United States
AU: La Force, M J
EM: laforce@sfsu.edu
AF: San Francisco State University, Department of Geosciences, San Francisco, CA 94132 United States
AB: Serpentine soils and their associated serpentine prairie habitats are extremely rare. Within California, serpentine-derived soil comprises only 2,860 km2 of the State and represents less than 1% of the total land surface. The Presidio, a National Park located in San Francisco, CA, hosts several patches of serpentine habitat, which are currently being encroached by non-native plant species. The serpentine soils support threatened and endangered plant species, and are defined by the geochemical properties inherent to the soils. We analyzed the physical and geochemical properties of soils within the West Grassland area of the Presidio to characterize the distribution of serpentine soils across the study site. Our goal is to further understand sub-surface conditions, including depth to bedrock and changes in lithology with depth. Nine locations throughout the West Grassland portion of the Park were randomly selected and hand augured to a depth of 3-5 feet, and soil samples were obtained at 1-foot intervals. Physical properties including color and texture were obtained in the field. Soils overlying serpentine bedrock were found to have a clayey-loam texture. Depth to bedrock was shallow in hilly areas underlain by resistant, hill-forming serpentine bedrock. Auguring further revealed that topographic lows correlated to changes in lithology from soils that were serpentine-derived to sandy loams consistent with sand dune deposits found elsewhere in the vicinity. The geochemistry of selected samples is being analyzed for namely pH, nitrogen, calcium, and magnesium concentrations. Geochemical data will be compared to an existing database and a statistical analysis of the geochemical data will be used to correlate physical and textural data.
DE: 0800 EDUCATION
SC: Education and Human Resourcese [ED]
MN: 2004 AGU Fall Meeting