E. Howe — Tuffs of the Soufrihe, St. Vincent. 319 



the valley fillings. Hovey says of tliem : ^'The chief of these 

 beds were formed in the Wallibon, Trespe and Rozean valleys, 

 on the. leeward (west) side, and in the valleys of the Rabaka 

 Dry River and its tributaries, on the windward (east) slope, with 

 by far the greatest thickness along the Wallibou and Rabaka 

 Dry rivers. In the valley of tlie AYalliboii the deposits were 

 not less than 60 feet deep in places, while in the Rabaka Dry 

 River the fresh material filled a gorge which is said to have 

 been 200 feet deep before the eruptions began." ^ These 

 tufl:*s, now well exposed in typical " bad-land " topography, 

 consist of a mixture of clay and fine grit, with numerous 

 coarser, angular rock fragments seldom larger than a clenched 

 fist. The prevailing color is a bluish gray where they are moist, 

 but some deposits of the September eruption, still hot and 

 causing secondary steam eruptions, are of a light reddish brown 

 or straw color. The ejecta of repeated eruptions, accumu- 

 lating layer upon layer, have produced a fairly well marked 

 stratification in these beds, the individual strata, for the most 

 part, consisting of unassorted materials. 



Resting in places upon the deposits just described, and 

 everywhere covering the hillsides and ridges, are accumula- 

 tions of quite a different kind, ranging in thickness from a few 

 inches to five or six feet. They are in all cases distinctly 

 stratified and extremely uniform in character. The lower 

 portions consist of typical unconsolidated lapilli, slightly 

 coarser than peas and becoming smaller in size upward, and 

 mixed with a fine sand until the top layer of the finest dust is 

 reached, the line between the two sorts of materials always 

 being a sharp one. This upper member has been converted 

 into mud by the rains and has subsequently hardened into a 

 firm crust, two to six inches thick, which protects the uncon- 

 solidated material below. On close examination, this crust is 

 found to consist of numerous layers or overlapping lenses made 

 up of small pellets of clay, as large as buck-shot, closely packed, 

 but not mashed, together. "When not too crumbling, portions may 

 be removed whose structure at once suggests that of an oolitic 

 limestone. Material of precisely the same character was col- 

 lected from the tuffs of Montserrat, and I w^as told that similar 

 layers have been found in the older deposits of St. Yincent. 

 Last summer, at the crater rim of Kilauea in the Hawaiian 

 Islands, Dr. AVhitman Cross collected a quantity of pellets, 

 which differ in no way from those that came from St. Vincent. 

 This structure would seem to be explained by the fact that at 

 the time of violent eruptions, and after the fall of the coarser 

 material, particles of dust still held in suspension would be 

 attracted to the globules of condensing steam, which, on fall- 



*0p. cit., p. 342. 



