The carbonate rocks of the Antigua Formation have been regarded as the reference series for the marine Oligocene of the Western Hemisphere since the pioneering work on Antigua (Fig. 1) by Vaughan (1919). Vaughan's work and sub-sequent additions to or comparisons with it have consisted largely of taxonomic and comparative paleontology. The general geology of the island has been reported on at intervals, largely by Europeans while the island was still a British colony (for example, Spencer, 1901; Brown, 1913; Earle, 1923; Trechmann, 1941; Thomas, 1942; Martin-Kaye, 1959, 1969; Christman, 1972). Most such reports are not by paleontologists, so the progress of knowledge of the geology and geologic history of Antigua has been dichotomous.
Frost has long worked to understand the community structure, ecology, and ecological succession of Oligocene organisms. The Antigua Formation (Fig. 2) is only locally coralliferous and does not contain the large volumes of massive reef rock that might be expected from the faunal lists for, the unit. Rather, it is a unit of soft and marly limestones, with some shaly or mudstone units, widespread sparse coral, foraminiferid, and molluscan debris in poorly cemented limestone, and local patch reefs in which these same fossil materials are abundant. The terrigenous material in the formation is largely of volcanic origin, as is most of the noncarbonate rock of the island.