ABSTRACT Barbados is actively rising in the latest phase of a long history of emergence that began as far back as 15 Ma. The current phase began at or before ca. 700 ka, is highly nonuniform, and at least locally, has been nonsteady. The uplift rate field in SE Barbados ranges between near-zero and 0.47 m/k.y. and is harmonic to active structures of NNW-SSE contraction. Emergence markers include limestone strata, coral, and shoreline angles, but we used only shoreline angles in calculations. We divided the capping limestone of windward Barbados into 10 units using physical criteria and dated them with over 40 230 Th ages as oxygen isotope stages 5a, 5e, late 7 and early 7, and old (older than 300 ka). The oldest unit is a relic of an earlier phase of emergence. Younger units, probably as old as 700 ka, downlap the eroded flank of the oldest unit and sublimestone foundation. Younger units comprise landward clastic facies deposited on abrasion platforms during eustatic highstand and seaward-coalescent fringe reef blankets deposited on preexisting slopes, mainly in transgression. Earlier models of ridged reefs of catch-up growth origin are not supported in windward Barbados. Shoreline angles, the updip tips of terrace floors and of younger limestone units, are isochronous markers of maximum highstand levels. Despite the lack of direct determination of their ages, shoreline angles provide the truest measures and highest values of emergence. Coral thought to indicate highstand growth gives moderately lower uplift rates due to depths of growth and collapse. Coral grown during transgression gives a marked error in emergence.

Abstract The surface and near-surface geology of the Atlantic Coastal Plain from Cape Fear, North Carolina to Cape Canaveral, Florida, below 76 m (250 ft) in altitude, comprises Pliocene and Pleistocene fluvial marine, back-barrier, barrier, and shallow-shelf sand, silt, and clay. The fossil content of age-equivalent Pliocene and Pleistocene sediments decreases from the Cape Fear area southward into Georgia. In the Carolinas, fossils are common. Paleontological analyses and isotopic and chemical age determinations, combined with lithostratigraphic studies and geologic mapping, have resulted in the establishment of a regional time-stratigraphic framework. In Georgia, fossils are scarce. Most known fossil localities are in early late Pliocene sediments paleontologically dated between 3.5 and 2.8 Ma. Microfossil data suggest the presence of at least two other Pliocene units—late early Pliocene (4.2-4.0 Ma) and latest late Pliocene (2.4-1.8 Ma). Fossil data are insufficient to differentiate Pleistocene units, but there are distinctive changes in shell morphology and species abundance of foraminifera in sediments topographically above and topographically below 9 m (30 ft) in altitude. No isotopic or paleomagnetic data are available for Pliocene or Pleistocene sediments in Georgia. There has been no detailed geologic mapping. Regional mapping dates to the turn of the century. The fossil-poor nature of both onshore and offshore Pliocene and Pleistocene Coastal Plain sediments in the Georgia part of the Atlantic Coastal Plain may be due to any one or combination of the following: styles and rates of regional and/or local uplift; sediment load of the numerous rivers that drain this region; freshwater influence on estuarine and nearshore littoral environments; shoreline configuration relative to major ocean currents; dissolution as the result of weathering, and erosion.

Abstract Many coastal areas of California and Oregon have emergent Quaternary marine terraces that have been assigned only indirect, approximate ages because of the paucity of suitable datable material for the U-series method, or because of the =40-ka limit of the radiocarbon-dating method. We report three thermoluminescence (TL) ages for clayey estuarine deposits from the San Simeon area of south-central California. A weighted mean TL age of 95±13 ka for clayey silt underlying marine deposits of the San Simeon ( Q ,) terrace suggests that this terrace correlates to oxygen isotope substage 5c (105 ka), or more likely substage 5a (80 ka). A single-analysis TL age of 230±70 ka for clayey beds in tilted estuarine deposits at San Simeon Bay is consistent with the available stratigraphic and age control for the underlying Careaga Formation (early Pleistocene or Pliocene) and the overlying Q p marine terrace (=60 ka). This TL age most probably compares to a time of high sea level at 200±20 ka (equivalent to marine oxygen isotope stage 7). The large analytical error in this TL age is consistent with deposition shortly before or after the =200 ka highstand of sea.

Abstract Over 165 species of megainvertebrates, mostly mollusks, from the lowest three (of approximately 17) emergent marine terraces along the southwestern coast of Santa Barbara County, California, provide the basis for both paleoecological and paleoclimatic interpretation. Most of the fossiliferous exposures on the two lowest terraces at Canada de Alegria, Gaviota, and Arroyo Hondo are situated at or very near to the original shoreline angle (i.e., base of the fossil sea cliff) of their respective terraces, physically constraining any interpretation of their depositional setting. The overall composition of their faunas, however, suggests sources from several near-shore marine habitats, all at intertidal to shallow inner sublittoral depths (0 to 18-27 m). Only the sandy bottom faunas from localities at Cojo Bay differ, representing a position about 700 to 750 m from shore and a water depth of about 15 m. Composite faunas from localities on the first terrace at Cojo Bay, Gaviota, and Arroyo Hondo, and from the second terrace at Canada de Alegria contain from four to 12 extralimital northern species each, indicative of slightly cooler water paleoclimatic conditions, comparable to those occurring today in the vicinity of Monterey Bay, central California. The fauna from the third terrace at Arroyo Hondo contains four extralimital southern gastropods, whose zoogeographic ranges suggest a more southerly geographic equivalency and slightly warmer water conditions, comparable to those occurring today between San Diego, California, and Ensenada, Baja California. On the basis of terrace mapping, uranium-series age estimates of bones, amino-acid racemization and epimerization analyses of bivalve mollusks, long-term uplift studies, and the zoogeographic signatures of the terrace faunas, the three lowest terraces are assigned ages of 85 to 80 ka (Cojo Bay, Gaviota, and lower Arroyo Hondo localities), 105 to 100 ka (Canada de Alegria second terrace locality), and 130 to 120 ka (Arroyo Hondo upper terrace localities), correlative with dated sea-level highstands recorded elsewhere as reef terraces, and in deep-sea sediments as marine oxygen isotope substages 5a, 5c, and 5e, respectively.