jSt. Vincent, and 2It. Pelee, Martinique. 327 



from this volcano fall on her deck when she was two hundred and 

 seventy-five miles east-southeast of St. Yincent. The steamer 

 encountered the dust at 10.30 P. x., May 7, eight and one-half 

 hours after the eruption of the Soufriere began, indicating trans- 

 port against the prevailing surface wind at more than thirty-two 

 knots per hour. Reports of vessels from the west (leeward) 

 of the island are curiously lacking. The dust was spread like 

 a gray mantle over the island, generally diminishing in thick- 

 ness from the crater outwards, but collected in vast deposits in 

 certain valleys on the sides of the mountain, where the condi- 

 tions seem to have been particularly favorable. The chief of 

 these beds were formed in the Wallibou, Trespe and Rozeau 

 valleys on the leeward side, and in the valleys of the Rabaka 

 Dry River and its tributaries on the windward slope, with by 

 far the greatest thickness along the Wallibou and Rabaka Dry 

 Rivers. In the valley of the Wallibou the deposits were not 

 less than sixty feet deep in places, while in the Rabaka Dry 

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

 been two hundred feet deep before the eruptions began (see 

 fig. 9). From a distance this deposit looks as if it were a 

 glacier coming out of the mountains. 



Such great accumulations of hot lapilli and dust retain their 

 heat for a lono^ time and thev ha\e o-iven rise to secondarv, or 

 superficial, eruption phenomena of striking character and con- 

 siderable interest. The river water and the water from the 



than in those of Mt. Pelee. The absence of chlorine is interesting as indi- 

 cating fresh waters as the source of the steam of the eruptions. 



SiOa 5O-08 



AI2O3 - 18-00 



Fe203 2 •46 / (Only approximate, because of effect 



FeO 4-57 )' of j)Trrhotite, 0-91 5^ — see below.) 



MgO 3-34 



CaO 7-74 



Na20 3 45 



KoO.. 0-65 



H.Oat 100' C 0-66 



H2O above 100' C 1-39 



Ti02 .. - 0-80 



ZrOa ? 



CO2 - - — none 



P2O5 0-17 



SO3 0-24 



CI none or faint trace 



S (0 "36) included in pyrrhotite below 



NiO none 



MnO 0-21 



BaO trace 



• SrO none 



Li20 faint trace 



Fe^Su?) 0-91 



99-67 



