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WALLACE E. PRATT 



clearly the characteristics already recorded in describing the ejecta 

 from Taal. I am confident that they originated in the same manner 

 in each case. 



The suggestion arises, in view of the foregoing observations, 

 that the condensation of mud into drops or balls must be a rather 

 common feature of volcanic eruptions which throw out great clouds 

 of water- vapor and fine sand or dust. The product may be 



Fig. 3. — Photograph showing close view of a face in a bed of clayey tuff con- 

 taining •'mud balls"; slopes of Mount Maquiling, southwestern Luzon. About one- 

 third natural size. 



described, perhaps, as a volcanic hailstone. Undoubtedly, the 

 contour of such bodies is often destroyed by the impact of the fall 

 to the ground surface. Probably only where the drops have had 

 opportunity to dry out somewhat before reaching the earth and 

 where they strike in soft, unconsolidated beds of recently fallen 

 tuff, is their form preserved under subaerial conditions. It would 

 appear to be equally remarkable that they should retain their form 

 upon falling into water. Yet it is beyond question that the tuff 

 series into which the wells at Bauan and Taal penetrated is in 

 great part water-laid, and it is to be presumed that the mud 



