Global Review of Upper Pleistocene (Substage 5e) Rocky Shores: Tectonic Segregation, Substrate Variation, and Biological Diversity

Markes E. Johnson, Laura K. Libbey

Abstract


A bibliographic search using the computerized system, Georef, allowed effective screening of the geological and paleontological literature for research articles on abandoned rocky shores correlated with oxygen isotope substage 5e (mid-point of the last interglacial epoch approximately 125,000 years before present). Sixty articles covering 54 localities with a global distribution were selected for synopses, including information on substrate lithology, present elevation, and faunal character. The sites are sorted by tectonic regime: 37% occur on active continental margins (modest uplift); 13% on passive continental margins (little or no uplift); 35% on island arcs (significant uplift); 15% on island chains or continental margins affected by hot spots (minor uplift to modest subsidence). In terms of their geographical latitude, the sites represent a range from temperate shores with dominantly molluscan faunas to subtropical shores with mixed molluscan and colonial coral faunas, to tropical shores with dominantly colonial coral faunas. During the peak of the last interglacial epoch, the subtropical limits were extended between 300km and 600km farther north and south than at present. Differences in biological diversity are difficult to gauge based on the highly selective species lists available in this data set. Nevertheless, enough information is at hand to clearly demonstrate that encrusting, intertidal to very shallow subtidal biotas are being retained in the geological record


Keywords


Last interglacial epoch; marine terraces; wave-cut platforms; unconformities

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