1890.] NATURAL SCIENCKS OF PHILADKLPHIA. 2^9 



AN ACCOUNT OF THE VINCELONIAN VOLCANO. 

 BY BENJAMIN SHARP, M. D. 



In no island of the West Indies, and probal)ly nowliere in the 

 "world does the student of vulcanology find, in so small a coni])ass, 

 such a field for interesting research as in the island of St. Vincent. 



If we take a boat and row from Kingstown, the capital, up the 

 leeward or western coast, we find the slopes of the volcanic hills 

 carved into deep valleys, which are separated from each other by vast 

 lava streams. The ends of these have been cut off by the never-ceas- 

 ing action of the sea and form perpendicular and often beetling 

 cliffs, from one hundred to one hundred and fifty feet high. On 

 these cliff faces we may read the expression of volcanic action, study 

 the character and extent of the ejections and note the different 

 periods of the eruptions. 



At the foot of the cliff, Avhere the sea has gnawed a deep groove, 

 there are large stones varying from the size of one's fist to a foot or 

 more in diameter. These were thrown from the crater first. Above 

 this layer and filtering between the larger boulders, is a stratum of 

 ash or mud which came down with the heavy rains that generally 

 set in soon after the eruption has begun. The mud is noAV hardened 

 into a compact mass enclosing the small boulders. Resting on the 

 ash layer and often many feet in thickness, is the solidified lava. 



On the top of the spur, in the loose soil that covered the lava, grow 

 rank grasses ; giant Cerei raise their gaunt candelabral forms, and 

 Florida moss, or as they call it here, " old man's beard," droops from 

 the many crevices. 



About a mile from the beach, at the mouth of the Cumberland 

 Valley, is a fine exposure of basalt, PI. IV, fig. 1. The cliflT, formed 

 of basaltic columns, faces the north, and forms the southern wall of 

 the valley, which runs east and west. The columns of basalt vary 

 from two to three feet in diameter and run perpendicularly to the 

 top of the cliff, which is about one hundred and fifty feet high. At 

 its foot runs a small stream, knc^wn as the Cumberland river. 

 There is no doubt but that this great lava stream extended across 

 the head of the valley which at this point is a mile and a half wide, 

 but what causes have been active in removing this enormous ma.-ss of 

 material, I was unable to determine. 

 20 



