Geological and Pltysical Development of Anguilla, 8fc. 323 



3. ' On the Geological and Physical Development of Guadeloupe.' 

 By Prof. J. W. Speucer, Ph.D., M.A., F.G.S. 



The Guadeloupe group is separated from the Antigua and 

 Dominica groups by depressions 2000 feet deep. Much of Guade- 

 loupe itself consists of eruptive rocks, evidently as old as the igneous 

 base of Antigua. The lowest beds of Grande Terre are yellow tufa, 

 surmounted by 75 or 80 feet of volcanic sand of eirly Tertiary age. 

 A calcareous formation conformably follows, dipping north-east- 

 ward. These two formations seem to correspond with the Oligocene 

 rocks of Antigua. The Lafonde Gravel and Marl succeeds them 

 unconformably, and it is possible that the limestone of the Usine 

 of Pointe a Pitre is of about the same general age. In addition to 

 these formations there are raised coral-reefs, consolidated calcareous 

 sands, alluvia, the loams and gravels of the Petit Bourg Series, and 

 various fragments of calcareous groups. The tooth of a small 

 Elephas, allied to the Maltese type, and found in Grande Terre, is 

 mentioned. 



The land-surface during the Mio-Pliocene period appears to have 

 been 2000 feet above the present level, but it was submerged 

 200 feet at the close of the Pliocene period during the accumulation 

 of the Lafonde and Lower Petit Bourg gravels and loams. There 

 was a re-elevation of about 3000 feet in the early Pleistocene 

 period, and during this epoch Elephas could have crossed from the 

 continent. This was followed by a depression to 100 feet or more 

 below the present level, a re-elevation to 150 feet, submergence below 

 the present level with growth of corals, and the elevation of these to 

 6 or 8 feet above the sea. 



4. 4 On the Geological and Physical Development of Anguilla, 

 St. Martin, St. Bartholomew, and Sombrero.' Bv Prof. J. W. Spencer, 

 Ph.D., M.A., F.G.S. 



Deep channels, not less than 1800 feet deep, separate the bank on 

 which this group is founded from the banks to the north and south. 

 The oldest rock of St. Martin and St. Bartholomew consists of 

 greenstone or dioritic porphyry usually much decayed, followed by 

 altered limestones, and volcanic ashes and breccias. The calcareous 

 divisions are associated with chert and deposits of manganese. 

 Fossils found in these rocks in St. Bartholomew determine the age 

 as equivalent to the Middle Eocene of Europe. A white limestone- 

 formation, which appears to correspond with the limestone-series of 

 Antigua, follows unconformably. The limestone is partly phos- 

 phatized at the surface and is pitted by caverns. It is apparently 

 succeeded by upper strata, with a modern fauna, similar to that of 

 the Pointo a Pitre Limestone of Guadeloupe. The limestones are 

 unconformably covered by mantles of breccia, gravels, and sand, 

 which maybe regarded as the equivalent of the Columbia formation 

 of the American Continent. The St. Martin plateau was a land- 

 surface throughout the Mio-Pliocene period, during the earlier part 

 of which it appears to have stood 2500 feet above its present level, 

 and was probably connected with the now neighbouring insular 



