Grading operations for the Rancho Del Oro/Town Center North shopping mall in Oceanside, California exposed and destroyed a series of Quaternary non-marine strata. These beds have been divided informally into three stratigraphic units. The lowest (unit 1) was deposited as a series of subaqueous sediment-gravity flows, and is inferred to represent deposition in a lacustrine setting. The middle unit (unit 2) is also inferred to represent a lacustrine setting, and consists of three fades representing beach, basin, and prograding delta depositional settings. Units 1 and 2 are the first recognized lake deposits in the Quaternary record of coastal San Diego County. Unit 3 is interpreted to represent stream deposition. Units 1 and 2 were fossiliferous, most notably including Deroceras aenigma, Anodonta, Physa, Microtus calijornicus, and Neochoerus. The occurrence of the fresh-water clam Anodontafrom unit 2 is the first record of this taxon from coastal San Diego County. The Neochoerus record from unit 1 is the first find of a capybara from the west coast of North America.
