364 
DRS. T. ANDERSON AND J. S. FLETT ON THE ERUPTIONS OF THE 
the Antillean volcanoes, which find their explanation in the peculiarities of their 
methods of eruption. They have been mostly explosive volcanoes, emitting ginat 
quantities of ashes, homhs, and ejected blocks, with occasional flows of lava. In 
this way great simple cones have been built up, mostly with one or more craters 
near their summits. Parasitic craters and lateral outlets have been rare, owing to 
the great strength of the volcanic structures, and as a rule the old orifices have been 
repeatedly made use of in the eruptive history with few and unimportant modifica¬ 
tions. This has been the story of the recent outbursts, and is in accordance with 
the structure of the best preserved dormant or extinct volcanoes of the Caribbean 
chain. They are simple cones, sometimes breached, or surrounded by an old “ Somma ” 
wall, and consist for the most part of ask with more or less abundant coulees 
of lava. 
So far as it was possible for us to ascertain, the geological structure of St. Vincent is 
very simple. All around the coasts the dip of the rocks as indicated by the great 
lava flows and the more persistent beds of ash, is outwards from the centre. On the 
leeward side the lavas dip to the west at gentle angles (averaging about 10°). At 
the south end and near Kingstown the dip is mostly south, while on the east or 
windward side the dip is also towards the sea. The ash beds are more irregular in 
this respect, and within short distances may show considerable variations. But, 
taken as a whole, they always agree fairly well with the dip of the lava flows, and 
they practically never show an inclination towards the centre of the island. We are, 
in fact, dealing with a highly eroded volcanic pile, a chain of old volcanoes, and the 
position of the craters and outlets must have nearly corresponded with the central 
ridge of hills. The radial outward dip is a reflex of the slopes down which the 
lavas flowed, and on which the ash beds gathered. Over these surfaces the streams 
ran in more or less direct courses to the sea. 
Along this central ridge, apparently, no craters, except that of the Soufriere, can 
now be found, and none are indicated on the map. Erosion, most rapid on the 
higher grounds, has already obliterated them. But it is there they are to be searched 
for, and though the task is a well-nigh hopeless one, the remains of them may yet 
be found. In all probability most of them are filled with agglomerate, but some 
may be represented by great bosses of crystalline rock like the Pitons of St. Lucia. 
We searched carefully in the streams which descend from the main ridges, and 
along the shores of the whole island for specimens of true plutonic rocks of dioritic 
character, but none were found, and this helps to demonstrate the comparatively 
recent nature of the whole island, and corroborates the evidence drawn from other 
sources as regards its geological history. 
It is, of course, possible to regard the island as an anticline or dome rising on the 
summit of a great earth fold, such as is indicated by the soundings on the charts as 
separating the Caribbean Sea from the Atlantic. But there are certain facts to be 
enumerated shortly which this would not explain, and in the whole island there is a 
