AN UNUSUAL FORM OF VOLCANIC EJECTA 



451 



PnsantSurfaca 



Virj fma ash 

 Hud balk (ash) 



and Banadero on the margin of the lake, from 6 to 8 kilometers 

 distant from the crater, must have been widely distributed; never- 

 theless, at the time I was inclined to attribute their formation 

 to accidental, rather than to common, conditions of explosive 

 volcanism. The literature accessible to me revealed little evi- 

 dence that ejecta of this character had been observed generally, 

 although the following description by Edward Otis Hovey of 

 "drops of mud," which he encountered after the eruptions on 

 Martinique in 1902, shows that simi- 

 lar phenomena have been noted : 



In addition to the showers of dry dust 

 and ashes, there fell during the eruption 

 an immense amount of liquid mud which 

 had been formed within the eruption cloud 

 through the condensation of its moisture. 

 This mud formed a tenacious coating over 

 everything with which it came in contact. 

 That drops of mud, too, formed in the air 

 and fell as a feature of the eruption is 

 proved by the condition of the walls the of 

 houses in Precheur, on which I found flat- 

 tened spheroids of dried mud which could 

 have formed only in the manner indicated. 

 These flecks of mud were two, four, and 

 even six inches across, where two or more 

 had coalesced. They occurred mostly on 

 the northern and eastern walls of the 

 houses. The testimony of the people as 



to the occurrence of rain during the great eruption is conflicting, but the evidence 

 of the coating and these drops of mud proves that much aerial condensation 

 of steam accompanied these outbursts. 1 



More recently I have come upon evidence which leads me to the 

 belief that the formation of mud balls has been rather character- 

 istic of that type of volcanic activity which results in the explosive 

 eruption of great clouds of dust-laden steam, at least where atmos- 

 pheric conditions similar to those on the island of Luzon prevail. 

 In the examination of samples of strata pierced in drilling for artesian 

 water at the towns of Bauan and Taal, distant 25 and 15 kilo- 

 meters, respectively, from the crater of Taal Volcano, abundant 



1 Edward Otis Hovey, Am. Jour. Sci., XIV (1902), 343. 



Former Surface 





Coarsi, 



Ash 



and 



Tuff 



Fragments 



fkdJ-zd Tuff 



Fig. 1. — Section of ash which 

 fell on the southwestern slope of 

 Taal Volcano in January, 191 1, 

 showing balls of dried mud near top 

 of layer. 



