LOCAL ENVIRONMENTAL PERTURBATIONS AS EVIDENCED BY SEDIMENTOLOGICAL ANALYSIS: SPITTAL POND, BERMUDA

Spittal Pond is located on the South Shore of Bermuda in Smith's Parish. The eight-acre pond is believed to have formed in an inter-dune lowland as three independent basins, which have since joined to form the present feature. The proximity of the pond to the Atlantic Ocean adds to the unique environmental character of the site.

Fieldwork conducted in June 2000 yielded eight vibracores ranging from one to five meters in length, limited by lithified Pleistocene eolianites at their bases. The cores revealed three distinct sediment types: a hemic (fiberous) peat, a sapric (desiccated) peat, and a gastropod and ostracod "sand" composed primarily of whole shell material. The peats appear to form in couplets with a transitional zone between the hemic and sapric layers. The sapric peat also is characterized by interbedded ostracod and gastropod "sands." The fact that the pond consists of three independent basins has resulted in three independent sedimentological sequences. The southwestern basin is best characterized by hemic and sapric peat couplets with a basal 14C date of 4320 +/- 40 years. The central basin contains not only the peats and "sands" but also includes 100 cm of basal clay that does not appear elsewhere in the record. The first peat in the central basin has a 14C age of 3760 +/- 40 years. Interbedded layers of sapric peat and the ostracod/gastropod "sands" dominate the northwestern basin that has a basal 14C date of 3640 +/- 40 years.

Over it’s 5000-year history, Spittal Pond can be characterized as operating within two distinct depositional regimes. One supported the accumulation of thick deposits of a hemic peat while the other favored development of sapric peat. The presence of gastropod/ostracod "sands" within the sapric peat layers is thought to be related to environmental perturbations within the pond that exceed the tolerance of these invertebrate comminutes.