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Late Quaternary fluvial history of Santa Cruz Island, California, USA

November 28, 2017

The geologic history of fluvial systems on Santa Cruz Island (SCI) is complex, involving responses to both allogenic and autogenic forcings. During periods of low or lowering sea level, canyons on the island were eroded and sediment was transported off the island onto the exposed marine shelf. When sea level rose, streams aggraded, building a sedimentary wedge that progressed from the shelf upstream into the canyons. This cycle of erosion and aggradation in response to glacial–interglacial sea-level cycles was likely repeated numerous times during the Quaternary, although clear evidence of only the most recent cycle is present in the island’s alluvial sequences. Christy, Sauces, and Pozo Canyons contain thick packages of fine-grained sediments that were deposited as a result of the interaction between autogenic depositional processes and allogenic forcing of continuous base-level rise. Other canyons on the island either have little alluvial fill due to their steep gradients or are filled with coarse-grained, recent (likely late Holocene) alluvium that covers the older alluvial deposits. Differences in the nature and extent of the alluvial exposures on SCI relative to those on neighboring Santa Rosa Island reflect differences in the local topography, geology, and ranching histories of the 2 islands.

Publication Year 2017
Title Late Quaternary fluvial history of Santa Cruz Island, California, USA
DOI 10.3398/064.078.0401
Authors R. Randall Schumann, Jeffrey S. Pigati
Publication Type Article
Publication Subtype Journal Article
Series Title Western North American Naturalist
Index ID 70202310
Record Source USGS Publications Warehouse
USGS Organization Geosciences and Environmental Change Science Center