are formed and longterm (500 years) Monte Carlo simulation including the 

 contributions due to sea- level rise and random storm occurrences. (Author). 



065 DAVIS, G. H. 1987. "Land Subsidence and Sea-Level Rise on the Atlantic 

 Coastal Plain of the United States," Environmental Geology and Water Science . 

 Vol 10, No. 2, pp 67-80. 



Land subsidence due to decline in head confined aquifers related to 

 municipal and industrial water pumpage , is widespread in the Atlantic Coastal 

 Plain. Although not a major engineering problem, subsidence greatly 

 complicated adjustments of precise leveling and distorts prediction of future 

 sea-level rise. When preconsolidation stress equivalent to about 20 m of head 

 decline is exceeded, compaction of fine-grained sediment the aquifer system 

 begins, and continues until a new head equilibrium is attained between fine 

 and coarse units. The ration subsidence/head decline is quite consistent, 

 ranging from 0.0064 in southeastern Virginia to 0.0018 at Dover, Delaware, and 

 Atlantic City, New Jersey. (Authors) . 



066 DAVIS, R. A., JR., and CLIFTON, H. E. 1987. "Sea-Level Change and the 

 Preservation Potential of Wave -Dominated and Tide-Dominated Coastal 

 Sequences," Nuramedal, D., Pilkey, 0. H., and Howard, J. D., eds . , Sea-Level 

 Fluctuations and Coastal Evolution . Special Publication No. 41, Society of 

 Economic Paleontologists and Mineralogists, Tulsa, OK, pp 167-180. 



The relative change in sea- level and the rate of sediment input 

 determine the character and the preservation potential of most coastal 

 sequences, although wave and tidal energy, and geomorphic and geologic setting 

 must also be considered. Progradational (regressive) coastal deposits are 

 more likely to be fully preserved than those of transgressive coasts. Modern 

 progradational coasts include numerous wave -dominated examples, (e.g., the 

 Nayarit coast of Mexico, the Georgia Bight, and the Washington coast near the 

 mouth of the Columbia River), and a few tide-dominated examples (e.g., the 

 German Bight) . In either situation, fairly complete shallowing-upward 

 sequences of subtidal to supratidal facies are preserved, because the 

 sedimentation rate exceeds dispersal by wave and/or tidal energy and the 

 effect of rising or falling sea-level. 



Transgressive sequences, which form where relative sea- level rise 

 exceeds net sediment accumulation, differ in degree of preservation. Wave- 

 dominated transgressive systems include the present coast of Delaware and the 

 outer banks of North Carolina. The Colorado River delta in the Gulf of 

 California represents a tide-dominated transgressive coast. Under wave- 

 dominated conditions, slow transgression with abundant sediment input and 

 moderate or low- incident energy will allow much of the sequence to be 

 preserved. A transgressive tide-dominated coast that is associated with low 

 sediment influx from land is characterized by shoreward transport of subtidal 

 sediment over the pre-existing facies. Present coastal conditions also 

 produce geographically juxtaposed progradational and transgressive sequences, 

 as on drumstick barriers. Such situations would generate a complicated 

 stratigraphic record. (Authors). 



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