STRATIGRAPHIC ANALYSIS OF TWO CORES FOR PALEOENVIRONMENTAL DATA, CAMP PENDLETON, CALIFORNIA

Two cores were collected from Camp Pendleton for the purpose of paleoenvironmental analysis of the sentiments during the month of February, 2011. R. A. Varney was present during field collection of the cores and able to make observations and assessments of the local environment. Upon receipt of these two cores, which were collected in the field with a truckmounted hydraulic corer, we proceeded to lay out all of the individual sections or drives of the cores for description and sampling. Radiocarbon dates were obtained as close to the bottom of each core as we were able to recover organic fragments. The goal was to examine to stratigraphic records of the Holocene from this basin. Potential analyses of the sentiments included pollen, phytoliths, diatoms, shells, macrofloral and faunal remains, and resistivity testing.
Previous stratigraphic reconstructions of the Ysidora Basin suggest that during the Early Holocene the area could best be described as a floodplain. By approximately 9400 an estuary had developed. Then between approximately 9400 and 5400 sediments and proxy records suggest transitions back and forth between an estuary and a lagoon. Finally, at approximately 5400 a salt marsh develops and persists for approximately 400 years before resurgence of the estuary. By approximately 3500 BP waters have receded or the basin has sedimented to a level that a floodplain has developed. No evidence of estuary, salt marsh, or lagoon conditions were noted between 3500 BP and present (Pope 2005:66-73).