THE HOLOCENE HISTORY OF WARWICK POND, BERMUDA

Warwick Pond located in the southwestern part of Bermuda is the only natural freshwater pond on the island. ¹⁴C dates recovered from basal sediments indicate an age of 2645 +/- 55 YBP. Six vibracores were extracted in a N-S transect from the pond in June 2001 to determine the sediment character, possible effects of rising sea levels, and to create a Holocene history of the pond. Representative samples were returned for organic carbon, grain size, grain morphology, and clay mineralogical analyses.

The basic sedimentological facies are similar in all the cores except for changes in relative thickness spatially. A basal clay greater than 90cm is overlain by a hemic (fibrous) "peat," the thickness of which varies across the transect with the thickest accumulation in the northern half of the pond. Hemic peat is overlain by alternating bands of ostracod "sand" and sapric (gelatinous) "peat." Overlying this is a unit that has been separated into poorly banded sapric "peat" intervals and well-banded sapric "peat" intervals. Modern unconsolidated sediments are found at the top. TOC values ranging from 9.6% to 51.5% indicate that most sediments are organic-rich sands instead of true peat. There are well preserved cycles consisting of a basal ostracod "sand" overlain by dark sapric "peat" bands without sand that then increase in sand content and become lighter in color upsection until the next ostracod "sand". A physical process such as a major storm event may explain this pattern by causing the resuspension of the pond sediments and concentrating the sand.