282 ReporU and Proceedings — Geological Society of London. 



3. " Ou the Geological and Physical Development of Guadeloupe."^ 

 By Professor J. W. Spencer, Ph.D., M.A., F.G.S. 



The Guadeloupe group is separated from the Antigua and 

 Dominica groups by depressions 2,000 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 early 

 Tertiary age. A calcareous formation conformably follows, dipping 

 north-eastward. 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 ^ 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 Mephas, allied to the Maltese type, and found in Grande 

 Terre, is mentioned. 



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

 been 2,000 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 3,000 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. " On the Geological and Physical Development of Anguilla, 

 St. Martin, St. Bartholomew, and Sombrero." By Professor J. W. 

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



Deep channels, not less than 1,800 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 Pointe a Pitre Limestone of Guadeloupe. The limestones are 

 unconformably covered by mantles of bi-eccia, gravels, and sand, 

 which may be 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 2,500 feet above its present level, 

 and was probably connected with the now neighbouring insular 



