506 PROP. J. W. SPKXCER ON THE GEOLOGICAL AND [NoV. I9OI, 



31. On the Geological and Physical Detelopment of Guadeloitpe. 

 By Prof. Joseph William Winthrop Spencer, M.A., Ph.D., 

 P.G.S. (Read April 24th, 1901.) 



Contents. 



Page 



I. Introduction 506 



II. Situation and Physical Characteristics 507 



III. jVotes on Guadeloupe proper and the Basement of the Island. 508 



IV. The Earlier Tertiarj^ Formations in Grande Terre 509 



V. The Lafonde Gravel and Marl 511 



VI. The Limestones at tlie Usine of Pointe a Pitre 511 



VII. Late Deposits and Coral-Reefs in Grande Terre 512 



VIII. The Petit-Bourg Series 513 



IX. Other Calcareous Fragments in Guadeloupe proper 515 



X. Remains of Elephas 515 



XL Erosion-Features , 515 



XII. Marie Galante, Desirade, Petite Terre, and The Saints 518 



XIII. Summary and Conclusions as to Changes of Level of Land 



and Sea 518 



I. Introdtjction. 



My visit to Guadeloupe in March, 1897, was for the purpose of 

 extending my observations of the later geological features of the 

 Antilles soiitlnvard from Antigua ; especially those bearing upon 

 the changes of level of land and sea since the early Miocene Period, 

 and their necessary variation in adjacejit localities. 



The features of the Guadeloupe archipelago present some striking 

 contrasts to tl)ose of the Antigua-Barbuda plateau. The main 

 island is divided into Guadeloupe and Grande Terre. The former 

 is Iravcised by high mountains, surmounted by recent volcanoes, 

 which are unrepresented in Antigua; but all these features are 

 reproduf^ed in Dominica and other islands of the western belt of 

 the Lesser Antilles. Grande Terre is a limestone-country comparable 

 with Antigua, and, therefore, forms the principal subject of this 

 paper. 



The islands of Desirade, Petite Terre, Marie Galante, and The 

 Saints, belong to the same physical unit as Guadeloupe — the three 

 former having characteristics similar to those of Grande Terre, and 

 the last, a group of seven islands, are remnants of the older volcanic 

 rocks. This archipelago is dissected to much greater depths tlian 

 the Antigua-Barbuda plateau, and shows modifications in the 

 erosion-features, helping us to further understand the history of 

 the Antillean plateau, most of which is now submerged. 



The earliest geological contributions appear to have been those 

 of William Maclure,^ shortly afterwards followed by the writings 

 of Alexandre Moreau de Jonnes.- Maclure's paper, along with the 



1 Journ. Acad. Nat. Sci. Philad. vol. i, pt. i (1817) p. 134. 

 - ' Ilistoire Physique des Antilles Fran^aises ' Paris, 1822. 



