Late Quaternary relative sea level in Southern California and Monterey Bay

Abstract

Few records of late Quaternary relative sea level (RSL) are available for the Pacific coast of North America south of San Francisco Bay, a region where RSL data would be particularly useful for constraining vertical rates of tectonic motion. This paper provides the first regional, uplift-corrected late Quaternary RSL history for southern California derived from a compilation of 132 previously published and unpublished radiocarbon ages from nearshore, estuarine, and freshwater deposits in sediment cores from coastal southern California. We also provide a local, uplift-corrected RSL history for Monterey Bay, central California, generated from 48 radiocarbon ages from Elkhorn Slough and surrounding environments. Our resulting compilations show rapid sea-level rise from 15 ka which begins to decelerate to present mean sea level (PMSL) between 6 and 8 ka. Late Holocene (<4 ka) sea-level rise averaged 0.8 ± 0.3 mm a−1 in southern California and 1.3 ± 0.19 mm a−1 along Monterey Bay in central California. Both rates of late Holocene RSL rise calculated are lower than recent RSL rates from southern California (∼1.61 ± 0.34 to 2.4 ± 1.04 mm a−1) and Monterey Bay (1.49 ± 0.95 mm a−1), derived from uplift-corrected, 20th century tide gauge data. This new RSL data fills geographical gaps in relative sea-level histories, as well as provides important datums for local tectonic processes.