428 
DRS. T. ANDERSON AND J. S. FLETT ON THE ERUPTIONS OF THE 
The Deposits in the Wallibu Valley. 
In that great depression which lies on the south side of the Soufriere, between that 
mountaiji and the Morne Garu, the ejecta of the recent eruption have accumulated 
to a far greater depth than elsewhere in the devastated country, and there, also, was 
the most complete destruction of vegetation, and the greatest loss of life. The 
western side of the valley is drained principally by the Wallihu Pviver, the eastern 
by the Pabaka Dry River, and the geological phenomena exhibited along the 
course of these streams and their tributaries are most interesting and important. 
The western valley, that of the Wallihu, is, as already described, uidike the 
common type of Antillean valleys, in being Inroad, open, and flat-bottomed, especially 
in the lower parts. The higher affluents which drain the southern flanks of the 
Soufriere have that steep-sided character, with drooping taluses of ash alternating 
with vertical cliffs of lava, which mark the mountain ravines of St. Vincent. But 
ill the lower parts of its course the Wallibu River has a comparatively gentle 
gradient, and along the coast at its moutli there is a considerable expanse of fairly level 
ground. This is separated from another similar valley, that of the Wallibu Dry River, 
on the north, by a flat-topped ridge which rises behind the plantation works 
of WalJibu. To the north of this, behind the Carib village of Morne Ronde, the 
mountain rises rapidly and steeply, while on the southern side the rugged mass 
of Ptichmond Peak overlooks the plain beneath. To the south, the Wallibu River 
is separated by a sharp-topped spur from the valley of the Ptichmond River, which 
also, in its lower part, has only a slight fall and a comjDaratively slow current. 
The Richmond Valley is carved in an old series of lavas and ash beds which seem 
to have proceeded from the Morne Garu volcano. They dip gently westwards to 
the sea. But the valleys of the Wallibu, and Wallibu Dry River have been cut out 
of that series of ash beds and coarse agglomerates (see Plate 30, fig. 2), well-bedded 
and without alternations of lava, which constitute the southern part of the Soufriere 
near its base, and are the record of the most recent phases of its volcanic activity. 
So soft is this material that on successive visits we could see that the streams flowing 
in it had deepened their channels by seimral feet in a couple of days. This may 
account for these rivers having reached an approximate base level before the others 
in the island. 
From the mouth of the Richmond River to that of the Rozeau Drv River along 
the coast, and thence up the valleys of the AVallilui and Wallibu Dry Rivers, the 
surface is covered with a mass of recent ash deposit of irregular and varying 
thickness (see Plate 25, fig. 2). It is thinnest on the hack of the ridge on which 
stands the dwelling-house of Wallibu-—where it attains the de 2 :)th of four or five 
feet. Here it was deeply furrowed with rain-illls, which had a ijinnate arrange¬ 
ment (see Plate 26), Tlie slopes on each side of this ridge are very steep and on 
them little ash I'ested ; the rains had already washed the greater part down upon 
