Statigraphic Evaluation of Buckridge Coastal Reserve Sediment System - Tyrell, NC Grant uri icon

abstract

  • An understanding of the underlying stratigraphy is critical to the prevention of salt-water intrusion and restoration of pre-logging hydrology in the Buckridge Coastal Reserve. The reserve is located between the confluence of two paleo drainages. During the sea-level lowstand associated with the last glacial maximum (approximately 18 to 20 thousand years ago) the paleo-upper Alligator River to the south and east drained a relatively large area that extended westward to the Suffolk Shoreline. To the north, the paleo-Frying Pan drainage was probably never more than a second order stream draining a relatively small area. Both of these drainage basins have been progressively filled with peat in response to the post-glacial (Holocene) climate change and resulting rise in sea level. As sea level approached its present elevation, progressive flooding with attendant shoreline erosion has removed previously deposited peat and created a broad expanse of water in the lower reaches of the Alligator River estuary. In the vicinity of Buckridge Coastal Reserve, the balance of peat accumulation versus peat destruction through shoreline erosion appears to be in mid-stage where the Alligator River narrows to a meandering pattern upstream. Ongoing subsurface studies in the Alligator River region as part of Parham's Pill research program indicate that peat deposits are generally underlain by a sandy mud unit upon which the surficial peat deposits were formed during the Holocene sea-level rise. This drowning surface has considerable paleo-topography (up to 25 feet) produced by the paleo-drainage system during the last glacial maximum. Thus, this clay surface not only determines the thickness and composition of the peat, but also forms a major confining layer upon which the shallow groundwater flows. The paleo-topography of this confining layer may playa major role in the encroachment and movement of salty water within the shallow ground water system.

date/time interval

  • May 2007 - December 2007