138 Scientific Proceedings, Royal Dublin Society. 



The process of dissolution of the salt beds by a natural process 

 of filtration, underground flow of waters impregnated with salt, and 

 their discharge in the form of springs, has been going on for a 

 lengthened period, extending back into pre-human times. Such 

 springs are still flowing in some places, notwithstanding the large 

 quantity of brine artifically extracted from the ground by pump- 

 ing. The flow of the brine springs must have materially aflected 

 the relative surface levels, and where, from some cause or another, 

 the dissolution has gone on more rapidly than in the surrounding 

 district, the subsidences would be more rapid, and a hollow would 

 be formed, into which the surface waters would flow and form a 

 lake or mere. In this manner it is probable all these peculia-r 

 sheets of water, generally lying in deep hollows, and known as 

 " the Cheshire meres," have been formed ; and when once formed, 

 the tendency would be for them to become larger as time went on. 



It may therefore be afiirmed that the origin of the Cheshire 

 meres and the Northwich subsidences is similar, only that in 

 the one case the process has been a natural one, in the other 

 artificial. 



