Correspondence — H. J. Johnston- Lavis. 239 



gravels, all these beaches are ranked in the scheme as newer than the 

 Chalky Boulder- clay. But the only Infra-glacial beach that is known 

 to occur within the region of the Chalky Boulder-clay, viz. that 

 which is at times clearly exposed at Sewerby on the Yorkshire coast, 

 is left entirely out of the reckoning. Thorough investigation of this 

 beach by digging and borings in 1887-90 enabled me to show that 

 it was older than the oldest ('Basement') Boulder-clay of the York- 

 shire coast, which is at least as old as the Chalky Boulder-clay. 

 Further, there can be no doubt that the Infra-glacial beaches of the 

 South of Ireland, with which I am well acquainted, are of practically 

 the same age as the Sewerby beach and stand in the same relationship 

 to the glaciation. There seeras every reason, also, for supposing that 

 the Infra-glacial beaches of South Wales belong to the same period. 



If Mr. Dewey be right in his correlation of the beaches of Devon 

 and Cornwall with those of the South of Ireland, it would follow 

 that they are older than the Chalky Boulder-clay, and not newer. 

 But, in the absence of Boulder-clays south of the Bristol Channel, 

 the correlation has still an element of uncertainty. Deposits of the 

 character of 'Head' and 'Combe Rock' are unsatisfactory materials 

 on which to base conclusions as to time-divisions of the Glacial 

 period, since it is clear that rubbles of this type were being formed 

 locally throughout the period in areas not covered by ice. In 

 Yorkshire, though the chief masses occur beneath all the Boulder- 

 clays, the rubbles are by no means confined to this horizon. 



G. W. Lamplugh. 

 St. Albans. 



April 13, 1913. 



SEA-WATEE AND CRITICAL TEMPEEATUEES. 



Sir, — I certainly have never written a paper with the actual title 

 referring to critical temperatures, but very much of my life has been 

 spent in promulgating the view of the solubility of H^O in fused 

 silicates and laying down the fundamental principles of varying 

 volcanic action based upon that as illustrated in fragmentary ejecta. 

 Neither the critical temperature of water nor the spheroidal state has 

 anything to do with the question, which, I have always maintained 

 and repeat, depends on the critical temperature and pressure of 

 solution of gaseous oxides (H^O), etc., in fused liquid oxides and 

 silicates. 



Curiously enough, my views have never been much referred to in 

 England, but are very generally accepted by Continental geologists, 

 which, if we are to believe Mr. A. R. Hunt, means that English 

 geologists read very little either the researches of their own country- 

 men or those of foreigners. 



Nine of my papers in the list mentioned by Mr. Hunt refer to the 

 subject under discussion, and I am now sending him a neAv list up to 

 date of 161 papers, in which four others treat of the same question. 



H. J. Johnston-Lavis. 

 Beaulieu-sur-Mer, France. 



April 7, 1913. ■ 



