Analysis shows the shallow subbottom is characterized by two continuous mappable acoustic horizons which lie nearly parallel to the present surface. The lower one lies at about 40 to 80 feet subsurface and is mid-Pleistocene in age. The upper sonic reflector lies between 10 and 40 feet below bottom, and correlates well with a marked lithologic change from overlying unconsolidated sediments to deposit partially lithified by blocky, mosiac, calcite cement.
Radiocarbon dates of intertidal shells and of overlying peats indicate this horizon is a pre-Holocene regressive surface. Slightly oolitic sediments comprising the layer are interpreted to represent a coastal complex deposited during a late Pleistocene (mid-Wisconsin) high sea level. Tertiary strata are truncated by a Pleistocene erosion surface lying at between -120 and -160 feet MSL. Overlying Quaternary sediments overage about 80 feet in thickness.
Surficial sediments adjacent to Cape Canaveral are medium to coarse, wellsorted quartzose-mollusk sand. Areal distribution and thickness (up to 40 feet) of this modern sand is directly related to topography: deposits are thickest beneath topographic highs, generally less than 5 feet thick on flat areas, and absent in depressions. Late Pleistocene regressive sediments, which locally crop out, and overlying mid-Holocene, transgressive coastal (lagoon, barrier) sediments, have been reworked and reshaped to form an undulatory surface of active sediments. Late Quaternary and modern deposition has centered around the large, south trending, cape-associated shoals. The large plano-convex isolated shoals lying seaward of cape shoals, particularly The Bull Shoal, represent remnants of earlier cape-associated shoals segmented and stranded during late Holocene sea-level rise.
Studies of area beach sediments show them to be derived from: erosion of the shoreface; onshore transport from adjacent shoal regions; and southerly longshore transport into the area. Petrology, faunal assemblages, and textural characteristics indicate that local coastal and shelf sources have been more important in the genesis of modern areal beach sands than southerly longshore drift.
Nearly all of the surficial sand deposits are suitable for beach restoration, and the thick deposits associated with topographic highs are the most suitable. Extensive deposits of sand suitable as a borrow source comprise The Bull, Ohio-Hetzel, Chester and Souteast Shoals, which have minimum volumes of 32, 79, 9, and 15 (x106) cubic yards, respectively. Volumes of suitable sand in surveyed portions of Chester Shoal and Southeast Shoal are likely an order of magnitude larger. Total volume of surficial medium-grained sands within the confines of the study area is over 2 x 109 cubic yards.
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