HR: 0830h
AN: H51D-1088    [PDF]
TI: Transverse drainage development along a tectonically active transform plate boundary (San Lorenzo River and Pancho Rico Creek, Monterey County, California)
AU: * Garcia, A F
EM: afgarcia@calpoly.edu
AF: Physics Department, California Polytechnic State University, San Luis Obispo, CA 93407 United States
AU: Stokes, M
EM: mstokes@plymouth.ac.uk
AF: University of Plymouth, School of Earth, Ocean and Environment, University of Plymouth, Plymouth, PL4 8AA United Kingdom
AB: Transverse drainage is often assumed to form as a result of either antecedence or superposition. Drainage-basin geomorphology in the Diablo Range of central California suggests that Pancho Rico Creek established transverse drainage as result of headward erosion, and drainage diversion caused by a landslide. Stream piracy may have also played a significant role. Mesoscale stream catchments within the Diablo Range of central California are elongate parallel to the NW trending San Andreas Fault zone (SAFZ). Principal streams draining these catchments ultimately flow to the west and form transverse drainages across the western ridges of the Diablo Range. Examples include the San Lorenzo River (SLR), which flows into the Salinas Valley at King City, and Pancho Rico Creek (PRC), which flows into the Salinas Valley at San Ardo. Incision patterns, fluvial stratigraphy, wind gaps, and beheaded, SW-flowing piedmont streams suggest that southeastward expansion of the SLR catchment occurred via headward erosion parallel to the SAFZ. Expansion occurred at the expense of SW-flowing piedmont streams, which were separated from the upland parts of their catchment by headward expansion of the SLR catchment. Preliminary results suggest that the upper PRC catchment was captured by the SLR after Qf2 time, but before Qt3 time. PRC recaptured its upper catchment when a Quaternary landslide (Qls) diverted both PRC and the SLR, an event that probably occurred after Qt3 time. Upper PRC drainage basin morphology also suggests recent stream capture. Thus, since Qls time, PRC has been a southeastward expanding transverse drainage.
DE: 1800 HYDROLOGY
DE: 1824 Geomorphology (1625)
DE: 9604 Cenozoic
SC: Hydrology [H]
MN: 2003 Fall Meeting