GEOLOGICAL SOCIETY OF MANCHESTER. 



551 



tioned, showing that the presence of animal remains being 

 embedded would not be inconsistent with the result of vol- 

 canic action. 



The next point considered was the probable origin of the 

 salt being attributable to volcanic action. Quoting from Mr. 

 Lyell's Principles of Geology, it was stated, that, in many 

 volcanic regions, jets of steam, which are often mixed with 

 other gases, issue from fissures ; and that, if such jets come 

 into contact with strata filled with water, they may give rise 

 to thermal and mineral springs. It was before mentioned 

 in the paper, that chloride of sodium was one of the emana- 

 tions of volcanic districts. A summary of some of the 

 principal mineral springs on the Continent was then given, 

 showing their rise in volcanic districts. In England, salt 

 springs were shown to rise in deep coal pits near large faults, 

 as at Patricroft and Pendleton. The same was shown to be 

 the case in the Durham and Newcastle coal-field; in which 

 district the salt was found rising from a vein of trap. The 

 saline springs were shown to rise from a fault in the coal 

 measures near Rowley ; and from the Silurian, altered by 

 trap, at Builth and in Radnorshire. 



The paper concluded with the following observations : — In 

 most, and probably in all these cases, their origin may be 

 distinctly traced to volcanic rocks. Had such springs flowed 

 into shallow hollows or lagoons, and from evaporation or 

 other cause, deposits taken place : had subsidencies from time 

 to time occurred, succeeded by fresh deposits of mineral and 

 other matter, a series of beds would be formed, such as are 

 now seen at North wich ; had the beds of salt been depo- 

 sited from a salt lake or the sea, in consequence of supersatu- 

 ration, the alternations of strata would, most probably, have 

 been comparatively regular in their thickness : such, how- 

 ever, is not the case. Again, as relates to the salt of the new 

 red sandstone, it is only found in insulated beds of the upper 



