. Coast watch. Marine resources; Oceanography; Coastal zone management; Coastal ecology. Approximate shoreline position during Yorktown formation [CAPE FEAR phate were deposited across the continental shelf. Although some geologists debate the source of the phos- phate, Riggs advocates a theory based on ocean upwellings. A buildup of phosphorus had occurred in the depths of the ocean. But during this formation, the phosphorus was transported from the ocean floor to the continental shelf. Riggs says this transportation occurred because of the location of the Gulf Stream. If sea level rises, the
. Coast watch. Marine resources; Oceanography; Coastal zone management; Coastal ecology. Approximate shoreline position during Yorktown formation [CAPE FEAR phate were deposited across the continental shelf. Although some geologists debate the source of the phos- phate, Riggs advocates a theory based on ocean upwellings. A buildup of phosphorus had occurred in the depths of the ocean. But during this formation, the phosphorus was transported from the ocean floor to the continental shelf. Riggs says this transportation occurred because of the location of the Gulf Stream. If sea level rises, the Gulf Stream moves inland. During the phosphate formation, the Gulf Stream was moving landward when it bumped into protrusions of the continental shelf. This deflected the warm surface current offshore and allowed the ocean water beneath to rise and spread over the continental shelf, according to Sea Grant oceanographer Len Pietrafesa. This cold nutrient-rich ocean is associated with phosphate formation. Riggs says eventually the Gulf Stream moved onto the shelf, cutting off the phosphorus supply and creating condi- tions that favored carbonate deposition. Because sea level fluctuated during this period, geogolists find alternating layers of phosphate and carbonate in this formation. The Pungo River formation is a valuable one for North Carolina. Phosphate is mined by Texasgulf Chemicals Co. near Aurora on the Pamlico River and processed into fertilizer. Some phosphate and carbonate were deposited in the lower layers of the Yorktown formation, which was formed between 3 1/2 and 5 million years ago. But this formation is made up largely of quartz. Continental margin tempera- tures alternated between warm and cold, and the shoreline stood west of present-day Wilson. The youngest geological formation, the Croatan, flooded less of the coastal plain (shoreline in the vicinity of Aurora). Warm seas during this era left behind dense layers of car- bonate shell hash. But sediment forma
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Keywords: ., bookcentury1900, bookcollectionunclibra, booksubjectoceanography
