Quaternary Sea-Level Events on Northern San Clemente Island, California

Abstract

Global sea-level changes are expressed in the coastal landforms and deposits of northern San Clemente Island. Stratigraphic, radiometric, amino acid, and pedologic dating techniques have allowed the development of a chronology of sea-level changes for about the last 500,000 yr. A uranium-series date on coral of about 127,000 yr for the 2nd terrace serves as a calibration point for amino acid age estimates of four other mapped terraces. Two of these terraces have age estimates of about 80,000–105,000 yr, another has an age estimate of about 127,000 yr, and the 5th terrace on the west side of the island is estimated to be about 415,000–575,000 yr old. These dates correlate reasonably well with marine terraces dated elsewhere and with stages of the oxygen-isotope record that are thought to represent high stands of the sea. Weakly cemented calcareous dune sands (eolianites) are moderately extensive on northern San Clemente Island and appear to represent low stands of the sea, since calcareous shelf sands were the most likely source. A radiocarbon date of about 22,000 yr suggests that the youngest eolianite was deposited during the last glacial maximum. An older eolianite is estimated to be about 140,000–195,000 yr old based on stratigraphic relations and degree of soil development. The suggested ages for the eolianites also correlate well with oxygen-isotope estimates of low sea levels.

Coastal tectonics on the eastern margin of the Pacific Rim: late Quaternary sea-level history and uplift rates, Channel Islands National Park, California, USA

“…Amino acid ratios in fossil Chlorostoma from independently dated terrace pairs (120 ka and 80 ka), collected in the present study, do indeed show good relative age discrimination, consistent with earlier studies of this genus (Wehmiller et al, 1977;Muhs, 1983Muhs, , 1985Muhs et al, 1992). D/L values for glutamic acid (Fig.…”

“…Consistent with past studies (Wehmiller et al, 1977;Muhs, 1983Muhs, , 1985Muhs et al, 1992), Epilucina does not seem to be as effective an age discriminator as Chlorostoma (Fig. 15).…”

“…For amino acid geochronology on the Channel Islands, the present study utilizes the common rocky intertidal gastropod Chlorostoma (formerly Tegula [McLean, 2007]), usually Chlorostoma funebralis (A. Adams, 1855) and the intertidal bivalve Epilucina californica (Conrad, 1837). Previous studies have shown that Chlorostoma is a reliable genus for amino acid geochronology, with Epilucina perhaps somewhat less reliable (Wehmiller et al, 1977;Muhs, 1983Muhs, , 1985Muhs et al, 1992). Relative abundances (using peak heights on chromatograms) of D and L enantiomers of the amino acids valine and glutamic acid were measured in fossil specimens of these genera, using reverse-phase liquid chromatography (Kaufman and Manley, 1998).…”

Renewed uplift of the Central Andes Forearc revealed by coastal evolution during the Quaternary

“…Each substage represents a long enough still-stand in sea level that can result in significant morphogenesis, but generally interglacial maxima (or peaks) corresponding to the highest highstands (e.g. MIS 5e) are best expressed in the landscape (Bull, 1985;El-Asmar, 1997;Lajoie, 1986;Muhs, 1983;Pedoja et al, 2006b;Pirazzoli et al, 1993). Thus authors typically relate terrace formation to one of the sea level highstands (column 'MIS' in Table 1), which generally offer much more precise timing constraints than the reported dating results.…”

Interpreting the Paleozoogeography and Sea Level History of Thermally Anomalous Marine Terrace Faunas: A Case Study from the Last Interglacial Complex of San Clemente Island, California

“…4,5), and terraces on the northern part of the island were mapped by Muhs (1983). In the Eel Point area (Fig.…”