Visualizing the Effects of Pleistocene to Holocene Climate Changes in the Bahamas: An Education Project Based on Research Conducted at the Gerace Research Centre

The tectonically stable carbonate platforms of the Bahamas are ideal features with which to demonstrate the effects of Pleistocene to Holocene climate changes. The effects of glacioeustatic sea-level changes and transatlantic dust transport on the complex depositional environments of Bahamian carbonate platforms have been interpreted by many field researchers using the extensively studied strata on the island of San Salvador. Much of this research has been conducted at, and published by, the Gerace Research Centre.

Synthetic orbital images are useful tools for introducing geology students to the sequential effects of past geologic changes on Earth surface environments (Griffing, 2002 & 2003). These images result from the assembly and digital blending of hundreds of fragments of real, scaled orbital photographs and real-color satellite images. Overview images of the Bahamian platforms and detailed images of San Salvador Island were generated for various times, in order to demonstrate the paleoenvironmental responses to Pleistocene-Holocene glacioeustatic changes. Since most currently exposed strata date from the last 500,000 years, these synthetic reconstructions have focused on paleogeography from the late Pleistocene to Holocene. Most notable are intervals of glacial lowstand, when the entire platform and portions of the high marginal slopes were exposed to form large, high cliff-bound islands, and the upper platform surfaces developed terra-rossa soils and dissolution features. In contrast, depiction of the Sangamon interglacial highstand (oxygen isotope substage 5e) shows sea-levels that exceeded current sea-level, as well as the inland development of reefs, lagoons and beaches. Representation of the Holocene sea-level rise also explains how the current eolian dune ridges developed off- and onshore. These paleoenvironmental reconstructions make the point to introductory students that an ice age can include numerous shorter-term climate changes, and give students that visit the Bahamas a better understanding of how pre-existing depositional topography influences later sedimentation.