Recent Relative Sea-Level Change in Eastern North America1
BARBARA V. BRAATZ, DAVID G. AUBREY, 1987. "Recent Relative Sea-Level Change in Eastern North America", Sea-Level Fluctuation and Coastal Evolution, Dag Nummedal, Orrin H. Pilkey, James D. Howard
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Eigenanalysis of tide-gauge records between 1920 and 1983 in eastern North America reveals highly variable spatial and temporal patterns of relative sea-level change. Auxiliary data from numerical modeling suggest that much of the long wavelength (thousands of kilometers) spatial patterns of sea-level change are due to postglacial isostatic adjustment of the land surface. Filtering the isostatic component from the rates of relative sea-level movement yields residual rates that fluctuate about a coastal mean of 1.0-1.5 mm/yr during this 64-yr time interval. This mean rate is within the range of previous estimates of mean rate of eustatic rise in sea level during the past century. Some residual fluctuations (wavelengths of tens to hundreds of kilometers) correlate with tilts of the land surface revealed by geodetic leveling transects, and appear to be related to regional geology (i.e., basement structures and tectonic provinces in Florida, Georgia, the Carolinas, and the Chesapeake Bay area; fault reactivation in northern New England and the Maritime Provinces). These results suggest that tide-gauge data can be used to determine neotectonic movements along this coastline. Analysis of the temporal patterns of relative sea-level change reveals a gradual increase in the rate of rise centered at about 1934, which may be due to steric expansion of the ocean. Broad peaks in the spectrum of temporal sea-level fluctuations at 3-, 6-, and 20-yr periodicities (significant at the 80 percent level) may be a reflection of oceanographic, atmospheric, and lunar forcing.
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Sea-Level Fluctuation and Coastal Evolution - This Special Publication is the result of a symposium in honor of W. Armstrong Price held at the first SEPM Midyear Meeting at San Jose, California, on August 12, 1984. The factors controlling relative sea-level change along our shores are varied and, at best, imperfectly understood. Yet, the relative rate of change is what controls shoreline erosion, the arrangement of sedimentary facies of the coastal zone, and the character of deformities within the coastal stratigraphic record. Therefore, these papers address sea-level changes, shoreline responses, and the controls on the three-dimensional geometry of the consequent lithosomes; in short, the architecture of the coastal depositional systems.