ERUPTION OF TAAL VOLCANO. 



71 



of their fall. Bedding planes could be distinguished in many fragments. 

 Generally, these tuff and agglomerate specimens were visibly impregnated 

 with sulphur, and often they were deliquescent from contained salts. 



The finer ejecta which have been referred to as mud or ash contain 

 a large proportion of clear, glassy fragments, some grains of glassy scoria, 

 both light and dark in color, and a residue of larger grains forming a 

 coarse, black sand consisting of basaltic pebbles and dark-colored mineral 

 grains. The material would be classed readily as a fine-grained andesite 

 tuff and is precisely similar in physical character to the finer grained tuffs 

 forming the crater walls. Fragments intermediate in size between the 

 large blocks and the finer ash occiir at the base of the mud-fall near the 

 crater as showTi in the accompanying text figure. Possibly some dry ash 

 fell on the volcaJio slopes, having been in the cloud too short a time to 

 be affected by the steam. A samjjle of the fitne ash taken on the upper 

 south slope of the volcano has been analyzed chemically in the laboratory 

 of general, inorganic and physical chemistry, Bureau of Science, and 

 appears on page 94. 



An interesting feature of the fall of the ejecta is the formation of 

 drops or balls of mud. These were most abundantly seen on the island 

 itself, but were observed at Ta- 

 lisay and Banadero also. They 

 range in size from large shot to 

 hazelnuts, and when broken some- 

 times show concentric markings. 

 Apparently they fell late during 

 the activity, being found just 

 below the surface of the deposit. 

 These mud balls can not be classed 

 as lapilli in the strict sense of 

 that term, since they were built 

 up, probably through the conden- 

 sation of steam into drops of 

 water. The accompanying ver- 

 tical section of the fall of mud or 

 ash (text figure Xo. 2) was taken 

 on the southwest slope of the 

 volcano. 



With the exception of the small number of incandescent stones, ejecta 

 from this eruption were apparently not much hotter than boiling water.^- 

 Obviously this was true of the mud which formed through the condensa- 

 tion of steam. The burns on the wounded were generally due to this hot 



/'resent Surface 



I 



Former Surface 



W 



Very fim ash 

 Mud balls (ash) 



Ash 



Coarsz 



Ash 

 and 

 Tuff 

 Fragments 



Baddod Tuff 



Text Fig. No. 2. 



" Brooks found the gases issuing from an exceptionalh: active vent in the 

 crater of Taal previous to this erupton to be at a temperature of only 420°. 



