370 
DES. T. ANDERSON AND J. S. ELETT ON THE ERUPTIONS OF THE 
St. Vincent is the occurrence of a well-marked submerged terrace off the south-east 
coast of the island. The soundings of the Admiralty chart show that opposite the 
mouth of the River Yambu the sea bottom slopes continuously down to a depth of 
150 feet in a distance of a mile, then for nearly a mile the depth does not perceptibly 
increase, hut the soundings are uniformly 24, 25, and 26 fathoms. To seaward of 
this flat ledge there is a gradual descent, and the 50-fathom line is often within a 
mile of its outer edge. Thereafter the slopes are ahnost precipitous, and there may 
be only one-third of a mile between the dejDths of 200 fathoms and of 50 fathoms— 
a slope of nearly 1 in 2 (see fig. 1). 
Evidently the 50-fathom line separates a gentle slope from one which plunges into 
the depths which lie to eastward of the lesser Antilles. Above that line we have a 
surface which has at some time or other been jiart of the land; below that we have 
the face of the great earth fold on the crest of which the Windward Islands stand. 
This is the real boundary of St. Vincent in a strict geographical sense. The flat 
ledge with an average depth of 150 feet can only be regarded as an old sea-cut 
terrace. Like the beaches on the windward shore it has no relationship to the 
geological structure of the country, and the slojDes cannot be old escarpments, as the 
dips are all seawards. It proves that the island formerly stood at least 150 feet 
higher, and was slightly more extensive in area than at present. 
Were it the case that on the windward side of St. Vincent there is a well marked 
series of raised beaches, while none can be traced on the leeward shores, this would 
be sufficiently remarkable to call for explanation. Undoubtedly there is no stretch 
of level ground on the western coast, nor are there well-developed terraces like 
those to be seen near Brighton, and elsewhere to windward, and it was not till 
after we had seen these, that it was possible for us to recognise and identify the scanty 
remains of similar features near Chateaubelair and Barrualli (see Plate 21, fig. 2). 
But even here there are occasionally level stretches on the headlands at heights of 
200 feet and more above the sea. They are narrow, and are most easily recognised from 
some short distance out at sea, where they appear as obvious breaks in the sloping 
sky-line presented by the ridges of the spurs. In one or two places (near Cumber¬ 
land) two or three can be made out, one above the other, with steeper intervening 
slojDes representing the old bluffs behind the shores. Their insignificant development 
is a natural consequence of the sheltered condition of this coast line. Erosion is 
much more rajDid on the windward side, where the billows, driven before the trade 
wind, jjound steadily against the rocks. The land-slopes on the western side also are 
steeper than on the eastern, so that sub-aerial erosion is more effective and the 
terraces (originally smaller) have been more raj)idly cut down and effaced. They 
occur, as might be expected, mostly on the rocky capes, and are never to be seen in 
the interior of the bays and valleys. They extend probably to as great a - height 
here as on the other side of the island, and belong to the same period of submergence 
and marine erosion. 
