The presence of beach ridges extending parallel to the present shore- 

 lines of many areas along U.S. coast indicates progradation of these areas 

 after the last glacial stage of the Pleistocene epoch. The general trend of 

 shoreline changes in the past 100 years, however, was erosion of several 

 hundred ft of the beaches. Three major causes are considered responsible for 

 such increased erosion. These are: (1) hurricanes and severe storms; 

 (2) recent eustatic rise in sea-level; and (3) interference by man with 

 natural shore processes. (Author). 



086 EMBRY, A. F. 1988. "Triassic Sea-Level Changes: Evidence From The 

 Canadian Arctic Archipelago," Wilgus, C. K., Hastings, B. S., Kendall, C. G., 

 Posamentier, H. W. , Ross, C. A., and Van Wagoner, J. C, eds . , Sea-Level 

 Changes: An Integrated Approach . Special Publication No. 42, Society of 

 Economic Paleontologists and Mineralogists, Tulsa, OK, pp 249-260. 



Triassic sea- level changes are not well documented because of a scarcity 

 of Triassic marine strata over many of the continental interiors and on 

 passive continental margins. An excellent laboratory for studying Triassic 

 sea- level changes is the Sverdrup Basin, which was a major depocenter in the 

 Canadian Arctic Archipelago from the Carboniferous to early Tertiary. Marine 

 Triassic strata are widespread across the basin and are as thick as 4,000 m. 



The established stratigraphic pattern for the Triassic succession 

 consists of thick progradational wedges of deltaic and marine strata, 

 alternating with thin, transgressive , clastic units (T-R cycles). On the 

 basin margins, subaerial unconformities cap the progradational wedges, and 

 over much of the basinal area, submarine unconformities form the cycle 

 boundaries. Nine T-R cycles occur in the basin and are interpreted as having 

 been generated by an interplay of eustatic sea-level change, gradually 

 decaying thermal subsidence, and variable rates of sediment supply and load 

 subsidence. In this model, rapid eustatic sea-level rises, coincide with 

 major transgressions that occurred in earliest Griesbachian, earliest 

 Smithian, late Smithian, earliest Anisian, early Ladinian, earliest Carnian, 

 mid-Carnian, earliest Norian, earliest Rhaetian, and earliest Jurassic. 

 Progradation occurred in the intervening time intervals under conditions of 

 slow eustatic sea-level rise, stillstand, and fall. 



The long duration of each of the sea- level cycles (about 5 million years) 

 and the apparent lack of Triassic glacial deposits indicate the cycles had a 

 tectono-eustatic origin that relates sea-level changes to changes in the 

 volume of the ocean basins. Sea-level rises are related to episodes of 

 increased rates of seafloor spreading and oceanic volcanism that resulted in 

 reduced oceanic-basin volume. The intervals of sea-level fall occurred when 

 seafloor spreading and associated volcanism were subdued and the ocean basins 

 gradually enlarged due to thermal subsidence. (Authors). 



087 EMERY. K. 0., and AUBREY. D. G. 1986. "Relative Sea-Level Changes From 

 Tide-Gage Records of Eastern Asia Mainland," Marine Geology . Vol 72, pp 33-45. 



Records from 22 tide-gage stations along the mainland coast of eastern 

 Asia document low- frequency vertical movements of the land perhaps biased by 

 unevaluated changes of sea-level. The land is rising (relative to sea-level) 



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