Tertiary depositional sequences beneath the continental shelf and slope 

 off New Jersey and Alabama have been studied using seismic-reflection data 

 that have been tied to available wells. These data illustrate second- (10-20 

 Ma) and third-order (1-5 Ma) depositional sequences in areas close to and 

 distal to progradational siliciclastic depocenters . Paleogene deposition is 

 characterized by sediment- starved deep-water conditions. Second-order 

 sequence boundaries divide these sediments and are recognized by local erosion 

 of underlying strata and deep-marine onlap . Closer to the depocenter, third- 

 order sequences are noted by basinward shifts in coastal onlap, local 

 erosional incision of shelf and slope strata, and planar erosion of basinal 

 sediments. The stacking pattern of third-order depositional sequences modeled 

 using a sinusoidally varying sea- level curve. Upper Oligocene to uppermost 

 middle Miocene third-order sequences are interpreted to compose a second-order 

 supersequence . Neogene strata in these areas are further analyzed to estimate 

 sea- levels. Subsidence is isolated using geohistory analysis and by 

 calculating the average angular -tilt rate of the continental margin. During 

 the early Tertiary, the subsidence rate was slow in both areas. An increase 

 in subsidence rate in the offshore Alabama area during the Neogene is 

 attributed to loading of the lithosphere adjacent to the study area. Short- 

 term falls in sea-level are estimated by measuring the vertical shift in 

 onlapping paralic strata from highstand to lowstand position. Results show a 

 lower overall Neogene sea- level position than the position represented on the 

 Exxon curve but similar magnitudes of short-term fall. (Authors). 



120 GRINDROD, J., and RHODES, E. G. 1984. "Holocene Sea-Level History of a 

 Tropical Estuary," Missionary Bay, North Queensland, In Thom, B. G. , ed. , 

 Coastal Geomorphology in Australia , pp 151-178. 



Earlier reconstructions of the course of the Postglacial Marine Trans- 

 gression (P.M.T.) in eastern Australia are based on either meager observations 

 or siommaries of observations from widely spaced sites (see Hopley, 1983) . 

 Thom and Roy (1983) construct a transgressional sea-level history for south- 

 eastern Australia based on a synthesis of data from a spread of sites from 

 southern Queensland to Tasmania. The data include revised radiocarbon dates 

 formerly reviewed by Thom and Chappell (1975) . Radiocarbon determinations on 

 a range of sea-level-related features are employed. An 'approximate zone of 

 sea- level' for the period 12,000 to 6000 radiocarbon years B.P. is fitted to 

 the data; the upper and lower limits of this area are defined by freshwater 

 facies and shallow water marine/estuarine facies, respectively. Belperio 

 (1979) provides a Holocene sea-level curve for the Townsville area in north- 

 eastern Queensland based entirely on radiocarbon dating of inferred mangrove 

 deposits, including 5 observations from 3 separate sites for samples collected 

 from transgressive deposits. Although both studies provide valuable informa- 

 tion regarding transgressive sea-levels in eastern Australia, their applica- 

 tion is limited for two main reason. Firstly, in the former study the nature 

 of the relationship between palaeo-sea-level and many of the samples dated is 

 imprecisely known (Thom and Chappell, 1975, p. 91). Secondly, as neither 

 study relies on data from a single location, precision in sea-level recon- 

 struction is potentially limited by between-site variations in the relative 

 heights of land and sea due to tectonic and/or isostatic adjustments in the 

 earths crust, and perhaps by differential rates of sediment compaction. 



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