TIDAL WETLAND RECORD OF HOLOCENE SEA-LEVEL MOVEMENTS AND CLIMATE HISTORY

Paleontological, geochemical, and lithological indicators of former ma rine and nonmarine influence are correlated between 13 cores from a ti dal wetland (Wolfe Glade) on the southeast coast of Delaware Bay. Twen ty new radiocarbon dates are used to establish the chronostratigraphy of marsh facies. Sediment iron content, weight loss on ignition, litho logy, and remains of plants, diatoms and foraminifera (known to tolera te specific tidal inundation cycles) are used to describe cored facies originating from supratidal, intertidal and subtidal salt marsh suben vironments. Pollen assemblages are used to infer local Holocene climat e fluctuations and to reconstruct paleoenvironments during marsh evolu tion. The record of paleoclimatology suggests the Atlantic Chron was w arm with variable humidity in the region, whereas the Subboreal was do minated by cool and humid conditions. The Subatlantic was warmer, and initially dryer, with a cool humid phase prior to about 1 ka, returnin g to warmer, humid conditions in the last several centuries. Local rel ative sea-level movements are characterized by five rapid, short-term episodes when the rate of sea-level rise accelerated relative to the r ate of marsh aggradation. These episodes are recorded by transgressive facies contacts at 5.3 +/- 0.2 ka, 4.4 +/- 0.2 ka, 4.0 +/- 0.2 ka, 3. 25 +/- 0.2 ka, and 1.8 +/- 0.2 ka, sidereal years. An earlier transgre ssive facies contact dated 6.9 +/- 0.2 ka is probably not the product of a true sea-level movement. Sea-level movements are recorded through out the marsh as palustrine or high marsh peats or peaty muds overlain by lower intertidal or subtidal marine deposits. Several features sug gest that these episodes are local relative transgressions produced by short-term accelerations in the rate of sea-level rise relative to ma rsh aggradation: the contemporaneity and apparent suddenness of marine inundations; the sequence of facies indicating marine drowning; the p resence of similar events in marshes elsewhere in Delaware Bay; and th e marsh-wide extent of indicative facies transitions. We propose that the rapid and frequent sea-level movements observed in Wolfe Glade are the result of surges and relaxations in the Gulf Stream (and associat ed spin-up and partial collapse of the North Atlantic gyre) in respons e to winds generated by changes in the North Atlantic atmospheric ther mal gradient associated with Holocene climate fluctuations.