RELATIONSHIP OF THE YOLCAXOES OF THE WEST INDIES. 203 



sea, in St. Eustatius, a similar pheiiomenon was repeated ; but 

 there the sea bottom was raised to a height of 900 feet, and 

 tlie prominence became surmounted by a crater now rising 

 about 2,000 feet above the sea. No eruptions in these islands 

 have been observed within the historic period. But this 

 locality is situated near the north-western end of the volcanic 

 chain. 



However, in the not distant island of Guadeloupe, several 

 eruptions occurred in the eighteenth and earlier part of the 

 nineteenth centuries, and in Dominica, a small disturbance 

 took place about 1880. While a small manifestation was 

 observed in Martinique some fifty years ago, yet the volcanic 

 forces had come to be considered inactive, and the only 

 danoerous volcanic island was thoug-lit to be St. Vincent, where 

 the eruptions of 1718 and of 1812 sent its cUhris as far as 

 Barbados, more than 100 miles away. 



The relationship of the volcanic activity to the physical 

 changes in the Antillean region should be somewhat more fully 

 explained, even though partial repetition may be unavoidable. 



In pre-Tertiary times the whole Caribbean plateau was 

 subjected to wide-spread volcanic eruptions which, however, do 

 not appear to have been entirely beneath the surface of the 

 sea, and later the plateau seems to have been a land surface, 

 which was greatly modified by atmospheric denudation 

 sweeping away any craters or cones that existed, and leaving 

 only modified hill surfaces such as now occur between the 

 Tertiary formations, or lie buried beneath the later volcanic 

 ridges. Even the origin of the plateau may have been mostly 

 volcanic, but that was antecedent to the early Tertiary period. 



While the old igneous basement is found beneath the surface 

 rocks of nearly all of the islands, yet we cannot certainly say 

 that the pre-Tertiary eruptions covered the whole breadth of 

 the submerged plateau between the Atlantic and Caribbean 

 basins ; for in Barbados upon its outer edge, there is a series of 

 sand deposits, probably as old as the later Cretaceous or early 

 Eocene days, which forms the oldest foundation in that region 

 of which we know anything. After the completion of the now 

 buried features carved out of these ancient eruptive rocks, and 

 after the deposition of the sandy shore deposits just mentioned, 

 the whole region sunk to depths unknown. In Barbados this 

 depression, perhaps referable to the same general epoch, 

 reached to the abysmal depth of perhaps two miles, as pointed 

 out by Professor Harrison and Mr. Jukes-Browne, the evidence 

 of which is shown by the oozes containing oceanic radiolaria. 



