ST. VINCENT IN 1902, AND ON A VISIT TO MONTAGNE PELEE. 
277 
The Wallibu District. 
The Wallibu valley, like its fellow, the Rabaka, though profoundly modified by 
denudation, is not primarily a valley of erosion, but a gap left between the mountains 
of the Soufriere and Morne Garu as they have been built up stage by stage. The 
slopes of Morne Garu to the south are formed of old tuff and occasionally lava, all 
dipping away from the centre of that mountain and with their surfaces sloping 
towards the valley more or less conformably to the dip. This was very evident when 
the surface was bare of vegetation in 1902 (Part I., Plate 29, fig. 2 ). The north 
slopes of the Wallibu district, including in that term the area drained by the smaller 
parallel rivers of the Wallibu Dry River, Trespe River, Morne R,onde, and others, all 
to the north of the Wallibu, are composed of a series of beds of a newer date formed by 
ejecta from the Soufriere. They dip away from the crater of that mountain and abut 
unconformably against the older beds of Morne Garu. They have been dissected into 
flat-topped plateaux (Plates 9 and 14) by the above-mentioned rivers, which run in 
deep gorges with steep and often precipitous sides. These gorges have again been 
filled in places by ejecta of later eruptions, and re-excavated in different degrees and 
sometimes not along the old lines, leaving plateaux and terraces of different ages and 
heights. The lower valley of the Wallibu is a good example of this.* The river as 
it descends from the mountains in a westerly direction turns abruptly to the south, 
and then to the west again, after which it flows by a straight course of almost two 
miles direct into the sea. 
The south or proper left bank of this lower portion was before the eruption of 1902, 
and is now again, moderately sloping and diversified by side gullies, almost deserving 
the name of valleys, in the old beds of Morne Garu, which show a fairly advanced 
stage of denudation. The north bank, on the other hand, is cut from a plateau, flat 
topped in the greater part of its extent, but with a rounded hill at its eastern end, 
and a moderate slope towards the sea on the west above the sites of the Richmond 
Estate House and Wallibu Works. Its top slopes gently to the south-west, and 
there is a terrace on the opposite bank of the river, near the lower end of the valley, 
which forms a continuation of the same slope, and shows that the plateau was once 
continuous across the valley which has since been excavated. Unlike the sloping 
bank opposite, it presents towards the valley a precipitous face in places nearly 
200 feet in height. In the 1902 eruption this part of the valley was filled by the 
incandescent avalanche to a depth of at least 100 feet in the upper part, and to a 
smaller extent towards the sea, and it was in this deposit of hot ash that the steam 
explosions, slips of hot ash, flows of boiling mud, and other secondary phenomena 
took place. They are illustrated in Part I., Plate 29, fig. 2 , where a deep channel is 
in progress of re-excavation on the south side of the valley, while a large plateau of 
hot ash still occupies its north side. 
* Part I., Map, Plate 39; Part II., Plates 9, 10, 11. 
