ABSTRACT The geomorphic evolution of southeastern windward Barbados is embodied in the development of a terraced seaward island slope on a tectonically rising scarp. The island slope is wholly erosional and a product of marine and subaerial processes. Modulation of the slope by terraces has occurred fundamentally by marine erosion at eustatic stillstands but includes morphologic additions by limestone deposition. The ongoing phase of morphologic development and island emergence began at or before ca. 700 ka. Emergence has proceeded at an increasing rate northwestward along the island’s southeastern coastline. The terraced island slope is markedly affected by post-terrace denudation. As many as eight marine terraces are preserved on the windward island slope below the planed surface of the Central Highlands, which is counted as terrace 1. Relics of an upper set of terraces are perched on the face of Second High Cliff, the ancient erosional margin of the oldest limestone capping Barbados. Second High Cliff developed by successive marine incisions over a probably long duration preceding oxygen isotope stage 9. A lower terrace set was excised in stages 9 through 5a in the siliciclastic island foundation or (and) in limestone cover of preceding terraces. Marine terrace floors extend seaward from an erosional backcliff and shoreline angle to a younger erosional cutoff. The most broadly preserved terrace floors indicate the following systematic succession of seaward profile elements: narrow upper ramp; broad upper flat; lower ramp; and on one, a lower flat. Carbonate cover is chiefly clastic on the upper ramp and flat, and chiefly reefal on the lower ramp. Most shoal-water reefal facies appear to be in fringe reef blankets. Terrace profile geometries are explained by a simple theory of wave abrasion in proportion to duration of sea level at a shoreline. At stillstands, the wave impact caused large shoreline recession and development of flats, whereas in transgression and regression, rapid sea-level change permitted only minor recession. Corresponding differences in cover facies are explained as functions of duration of breaking waves and seabed stability. Widespread post-terrace denudation is attributed to floods of upland provenance, local overland flow, and marine flooding. Riverine processes have produced channelization and a high degree of terrace preservation on the interfluves in the steeper, foundation-based northern windward region. This differs markedly from the more diffuse, shallow gullying and stripping of the limestone-covered shallow slopes of the southern region. An intensely stormy spell is suggested between stages 5e and 5c.

The Grenadine Islands and the marine environment surrounding the islands were mapped over a five-year span. The project—Grenadines Marine Resource and Space-Use Information System (MarSIS)—involved merging local knowledge with existing scientific data into a geographic information system (GIS). Located in the Caribbean, the Grenadines share an international boundary between Grenada and St. Vincent and the Grenadines, creating numerous challenges for not only collecting data but sharing those data with the residents of the islands. Project geospatial information was collected in a GIS, but Google Earth was used as a way to share the findings on the web and through a series of tutorials and workshops. Though project GIS shapefiles will be made available through the project website, Google Earth was used as a ready delivery tool because it is cross platform, easy to use, and free. Using aftermarket GIS extensions, shapefile layers were exported from ArcGIS into Keyhole Markup Language (KML) layers. Over 400 photographs and videos were geolocated in the project KML. Once the Grenadines marine map was assembled as a KML project, we gave workshops on various islands. From user feedback following the first series of tutorials, we modified the KML by fixing problems, correcting mistaken information, and making the KML project file more understandable. When the project was finalized we put the KML on the MarSIS project web page and sent it as an attachment to the project email list. We traveled a second time to the Grenadine Islands to give another series of tutorials and workshops. We also created a video to help users navigate the project KML.