A Sea Level Database for the central Pacific coast of North America.

TitleA Sea Level Database for the central Pacific coast of North America.
Publication TypeJournal Article
Year of Publication2015
AuthorsEngelhart SE, Vacchi M, Horton BP, Nelson AR, Kopp RE
JournalQuaternary Science Reviews
Date Published04/2015
KeywordsCascadia subduction zone, Glacial isostatic adjustment, Holocene, Pacific North America, Sea-level database

A database of published and new relative sea-level (RSL) data for the past 16 ka constrains the sea-level histories of the Pacific coast of central North America (southern British Columbia to central California). Our reevaluation of the stratigraphic context and radiocarbon age of sea-level indicators from geological and archaeological investigations yields 600 sea-level index points and 241 sea-level limiting points. We subdivided the database into 12 regions based on the availability of data, tectonic setting, and distance from the former Cordilleran ice sheet. Most index (95%) and limiting points (54%) are <7 ka; older data come mainly from British Columbia and San Francisco Bay. The stratigraphic position of points was used as a first-order assessment of compaction. Formerly glaciated areas show variable RSL change; where data are present, highstands of RSL occur immediately post-deglaciation and in the mid to late Holocene. Sites at the periphery and distant to formerly glaciated areas demonstrate a continuous rise in RSL with a decreasing rate through time due to the collapse of the peripheral forebulge and the reduction in meltwater input during deglaciation. Late Holocene RSL change varies spatially from falling at 0.7 ± 0.8 mm a−1 in southern British Columbia to rising at 1.5 ± 0.3 mm a−1 in California. The different sea-level histories are an ongoing isostatic response to deglaciation of the Cordilleran and Laurentide Ice Sheets.