GRENADA. 231 



Montserrat, the western half of the deeply incised Guadeloupe, Dominica, Martinique, St. 

 Lucia, St. Vincent, the Grenadines, and Grenada. These islands form a continuous circular 

 arc, and some of them inckide three to four eruptive centres — Martinique, according to 

 .Tonnes, even six. 



"The next zone comprises the great and rich mountainous islands of the Greater Antilles 

 and the narrow but well-characterized border of the Lesser Antilles. The mountains are 

 formed in complete accordance with the type of the Coast Cordilleras of the south and of the 

 mountains of Venezuela. The oldest organic remains belong to the lower Cretaceous, and 

 these are only represented by a few traces; on the other hand, purer and highly fossiliferous 

 limestone deposits of the Turonian are present in this region, as in Trinidad and in north 

 Venezuela. The Cretaceous system is followed here, as in Trinidad, by a largely developed 

 series of Tertiary deposits, some members of wliich present an astonishing resemblance to 

 their representatives in Europe. These deposits form the connecting link with the third zone. 



To this second group belong Cuba and Pinos Island, Haiti, Porto Rico, the Virginian 

 Islands with St. Croix, Anguilia, St. Bartholomew, Antigua, the eastern half of Guadeloupe 

 and a part of Barbados, and further the southern arc which runs through Jamaica. That 

 part which lies in the Lesser Antilles forms a girdle running outside the volcanos. 



The third and outermost zone comprises oiily middle Tertiary or even more recent deposits. 

 It no^\'here rises in mountain ranges which can be properly so called, and is, indeed, as a rule, 

 quite flat, broader towards the north-west, narrowing away to the south-east. It includes 

 the Bahamas, all the banks of trifling height which succeed as far as Natividad, then Anegada, 

 Sombrero, Barbuda, and a part of Barbados. I should, however, be inclined to include in 

 this zone the whole peninsula of Florida, and perhaps even the level part of Yucatan. 



"This regular arrangement of the islands was already clearly recognized in its main 

 features by Leopold von Buch. ' All the volcanic islands of the Antilles, ' wrote the great 

 geologist more than sixty years ago, ' follow one after the other in a continuous chain, uninter- 

 rupted by any islands which are not volcanic. On the other hand, there appears to the east of 

 these islands, lying outside them next the great ocean, another series of islands, somewhat 

 less clearly marked, which exhibits only a few traces of volcanic phenomena, and contains no 

 active volcanoes. This is an extremely remarkable fact!' 



From the above it will be seen tliat Grenada belongs to the first zone of 

 islands, and is the most southern member of that chain. While Suess character- 

 izes them as "wholly of recent volcanic origin," he can not mean that these 

 islands arose from the sea, each independently, but rather that they represent 

 in some cases each as many as four or six eruptive centres which have broken 

 out along the mountain chain which made up the entire Greater and Lesser 

 Antillean region. 



The tilting into the Caribbean sea of Antillea, and the consequent slipping 

 of tlie great, thick beds of which it was composed, may explain why each of the 

 three concentric arcs of islands has a homogeneous structui-e while it is still 

 intimately related to the conformation and structure of the other two groups. 



The composition of these arcs was briefly described above. In the inner 

 group volcanos have arisen along the great joint plane, and have flowed out so as 

 to overlie much of the older rocks, which nevertheless exist as the following quo- 



