No abstract

Bermuda, where Pleistocene eolianite was first named and analyzed in terms of glacioeustasy, can be considered the type locality of the carbonate eolianite facies. In Bermuda, this facies consists of bioclastic eolianite and associated beach deposits, weakly developed calcarenitic paleosols, and red to reddish brown paleosols termed "terra rossa" by many authors. The eolianite formed as large retention ridges, which prograded inland into a vegetated landscape; the sediment was derived from the surrounding submerged platform. Eolianite deposition in Bermuda was an interglacial phenomenon. It occurred mainly after the initial submergence, which is recorded by deposits of rocky shorelines and pocket beaches like those of the present-day erosional coastline. The terra-rossa paleosols represent relatively long hiatuses in the carbonate buildup, and therefore intervene between the limestones of successive interglacial stages; however, these paleosols do not equate exactly to glacial stages. The weakly developed calcarenite paleosols represent minor breaks within and between interglacial substages.Although sea-level history is the ultimate control of the mosaic of facies and the succession of stratigraphic units in Bermuda, attempts to define lithostratigraphic units in terms of sea-level history led to unmappable columns. Lithostratigraphic units now have been mapped successfully throughout Bermuda. These units parallel time-stratigraphic units but, in themselves, do not permit resolution of successive interglacial stages in the lower part of the column. Enhanced resolution is provided by allostratigraphic and aminostratigraphic units. The latter are zones defined by amino acid racemization (AAR) ratios that provide a measure of relative age. By use of interpretive kinetic models, the ratios have been converted to age estimates that allow direct correlation with the deep-sea oxygen isotope stages.Among the principal findings of stratigraphic mapping and analysis in Bermuda are: that shoreward superposition (lateral accretion) is the key mapping principle; and that the stratigraphic column includes a significant record of oxygen isotope stages 5, 7, 9, and 11, as well as an older history represented by the Walsingham Limestone at the base of the exposed section.

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The warm climate of Bermuda today is modulated by the nearby presence of the Gulf Stream current. However, iceberg scours in the Florida Strait and the presence of ice‐rafted debris in Bermuda Rise sediments indicate that, during the last deglaciation, icebergs discharged from the Laurentide Ice Sheet traveled as far south as subtropical latitudes. We present evidence that an event of similar magnitude affected the subtropics during the Last Interglacial, potentially due to melting of the Greenland Ice Sheet. Using the clumped isotope paleothermometer, we found temperatures ~10°C colder and seawater δ18O values ~2‰ lower than modern in Last Interglacial Cittarium pica shells from Grape Bay, Bermuda. In contrast, Last Interglacial shells from Rocky Bay, Bermuda, record temperatures only slightly colder and seawater δ18O values similar to modern, likely representing more typical Last Interglacial conditions in Bermuda outside of a meltwater event. The significantly colder ocean temperatures observed in Grape Bay samples illustrate the extreme sensitivity of Bermudian climate to broad‐scale ocean circulation changes. They indicate routine meltwater transport in the North Atlantic to near‐equatorial latitudes, which would likely have resulted in disruption of the Atlantic Meridional Overturning Circulation. These data demonstrate that future melting of the Greenland Ice Sheet, a potential source of the Last Interglacial meltwater event, could have dramatic climate effects outside of the high latitudes.

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The history of sea level in regions impacted by glacio-isostasy provides constraints on past ice-sheet distribution and on the characteristics of deformation of the planet in response to loading. The Western North Atlantic-Caribbean region, and Bermuda in particular, is strongly affected by the glacial forebulge that forms as a result of the Laurentide ice-sheet present during glacial periods. The timing of growth of speleothems, at elevations close to sea level can provide records of minimum relative sea level (RSL). In this study we used U-Th dating to precisely date growth periods of speleothems from Bermuda which were found close to modern-day sea level. Results suggest that RSL at this location was above modern during MIS5e, MIS5c and MIS5a. These data support controversial previous indications that Bermudian RSL was significantly higher than RSL at other locations during MIS 5c and MIS 5a. We confirm that it is possible to explain a wide range of MIS5c-a relative sea levels observed across the Western North Atlantic-Caribbean in glacial isostatic adjustment models, but only with a limited range of mantle deformation constants. This study demonstrates the particular power of Bermuda as a gauge for response of the forebulge to glacial loading, and demonstrates the potential for highstands at this location to be significantly higher than in other regions, helping to explain the high sea levels observed for Bermuda from earlier highstands.

Highlights • New U-series dates for coral fragments confirm a MIS7 age for emergent, Belmont Formation, marine deposits on Bermuda • New sedimentary evidence reliably establishes the elevation of relative palaeo-sea-levels • First description of widespread Quaternary faulting in Bermuda • We challenge the concept of Bermuda as a stable "tide-gauge" for Quaternary sea-level. Three new U-series ages from coral fragments found in the Belmont Formation of Bermuda fall in a range of ~198 ka to ~ 196 ka. These late MIS 7 ages are consistent with those of ~201 ka and ~199 ka measured in a previous study. The disputed interpretation of the Belmont Formation as a unit that is allostratigraphically distinct from subsequent MIS 5e deposits, of the Rocky Bay Formation, is vindicated by a minimum age of 196 ±3 ka for the total of 6 coral fragments it has yielded. Emergent marine deposits of the Belmont Formation include sedimentary lithofacies that are considered to be reliable relative sea level indicators. Prominent among these is a facies representing the "beach step": a feature that develops sub-tidally, directly at the base of the swash zone. From this facies, and others preserved along 6 km of Belmont Formation coastal exposure, it is concluded that MIS 7 relative mean sea level reached +4.5 m, and likely peaked at or above +6.0 m, relative to present sea level at Bermuda. Lower MIS 7 sea level positions that are evidenced and that have been quoted, in the past, are considered transitory positions, not maxima. The MIS 7 sea-level elevations on Bermuda, reconstructed in this study, are well above the majority of those reported from elsewhere in the world. This challenges the long-standing notion of Bermuda as a vertically stable "tide-gauge", but is consistent with glacio-hydroisostatic models which predict land-mass subsidence at intermediate field sites, such as Bermuda, at the end of long interglacials. However, because of evidence of instability at Bermuda in the form of seismic activity and faulting, which require further investigation, judgment is reserved on the global implications of this palaeo-sea-level anomaly. ,

Rowe, Mark P., 2011. Rain Water Harvesting in Bermuda. Journal of the American Water Resources Association (JAWRA) 47(6):1219–1227. DOI: 10.1111/j.1752‐1688.2011.00563.x Abstract:  Roof‐top rain water harvesting is mandated by law for all buildings in Bermuda and is the primary source of water for domestic supply. The average rate at which rain water is harvested at the typical house with four occupants is, however, insufficient to meet average demand. While just over one‐third of households have access to supplementary water either from mains pipelines or private wells, the majority rely on deliveries from water “truckers” (tankers) to augment their rain water supply. Assuming a reasonably constant daily demand, there is a linear relationship between the “maximum optimum capacity” of a water storage tank and the size of the rain water catchment area, which depends on the characteristics of the rainfall at a given geographic location. A simple spreadsheet model was developed to simulate tank storage levels for various combinations of catchment area, tank capacity, and demand, with an input of actual daily rainfall data for a study period of nearly three years. It was found that for typical cycles of rainfall surpluses and deficits in Bermuda, the tank capacity which there is no benefit in exceeding — the “optimum maximum capacity”— is 0.37 m3 of storage capacity per 1 m2 of catchment area. Furthermore, it was concluded that many domestic water storage tanks in Bermuda are larger than necessary, especially so where there is a significant imbalance between rain water supply and demand.