The Origin of Rock-Salt. 39 



say of it here that it seems to me to confirm the conclusions 

 I had previously announced, and also to prove conclusively 

 that no estimate of the quantity of salt in the sea can be a 

 factor of any value in calculating the Age of the Earth. 



The following notes, which were in my original manu- 

 script, but, on account of want of time, were not read at 

 either meeting of the Eoyal Physical Society, are inserted 

 here. They relate to the geological distribution of salt, to 

 its associated minerals, to its influence upon the various 

 metals, and to one or two other points of more or less 

 scientific interest : — 



Nearly the whole of the deposits of salt occurring in the 

 fossil state are found associated with strata which bear 

 independent evidence of having been formed within areas of 

 inland drainage, and most commonly during conditions of 

 more or less aridity. I should regard all of these as 

 representing salt derived from the sea through the atmo- 

 sphere. Some few instances occur of salt of Proterozoic 

 age, a few more date from the Deuterozoic period. Most of 

 the western and central European saliferous deposits are of 

 the age of the Trias, including the famous deposit at Middles- 

 boro in Yorkshire, which occurs on the same platform as the 

 gypsum of Cumberland, in the Bunter Marl. Seeing that 

 the so-called " Permian " is only an older part of the same 

 formation, accumulated under the same conditions as the 

 Trias, there is no reason why some salt should not be of this 

 age also. 



Then, seeing that desert conditions and inland lakes must 

 have had a place during each geological period on some one 

 part or another of the earth's surface, there is every reason 

 to expect to meet with saline deposits wherever such con- 

 ditions happened to obtain. Accordingly, we find that there 

 is hardly a single geological period, especially from the 

 commencement of Neozoic times, which has not, in one part 

 or another, its deposits of Eock-Salt. This being the case, 

 there is no need to give a list in a paper like this. 



As regards the associates of rock-salt, it has long been 

 known that Dolomite, Anhydrite, and Gypsum are nearly 

 always more or less closely associated with Eock-Salt. An 



