[bailey] gypsum deposits OF NEW BRUNSWICK 11 



saturated solution of common salt this change (from gypsum to anhy- 

 drite) takes place at 30° C, which is a temperature reached on a sum- 

 mer day. This fact satisfactorily accounts for the formation of anhy- 

 drite in nature from concentrated sea water or lake brines." Van't 

 Hoff, also, in his work on the German salt deposits, has made it very 

 probable that the presence of saline matter has a marked influence upon 

 the form in which the lime sulphate is deposited. Geikie, in his 

 Text-Book of Geology, page 115, in alluding to various possible 

 methods of the formation of gypsum, says, " It may be produced as a 

 chemical precipitate from solution in water, as when sea water is eva- 

 porated ; also through the hydration of anhydrite '' ; adding that " it 

 is in the first of these ways that the thick beds of gypsum associated 

 with rock salt in many geological formations have been formed." 



We may now briefly consider the facts presented by the gypsum 

 deposits of l^ew Brunswick in the light of the theories above noted. 



It has already been shown that the geographical and physical con- 

 ditions prevailing in this part of America at the time of the Lower 

 Carboniferous formation were favourable for the production of evaporat- 

 ing basins or lagoons, similar to those which are believed to have char- 

 acterized portions of the State of Xew York during the Salina period; 

 and from the occasional occurrence of corals in the limestones, and of 

 Tree Ferns (megapliyta) in certain beds of the overlying Millstone 

 grit, we may infer that the temperature conditions were equally favour- 

 able. Supposing, however, the whole of the original deposition to have 

 been in the form of gypsum and that this was dehydrated as the result 

 of deep burial and consequent thermo-metamorphism, we have to en- 

 quire as to the possible thickness of overlying sediments necessar}^ to 

 determine this result. These would necessarily consist largely of the 

 rocks of the coal-formation. Now these, so far as the beds of the Mill- 

 stone grit and the ]\Iiddle Carboniferous era are concerned, are well 

 kno-R-n to have, over the greater part of New Brunswick a very insigni- 

 ficant thickness as compared with the same rocks in Nova Scotia, reach- 

 ing a maximum, and that only in one locality^ of a little over 1,000 

 feet. The thickness o£ the upper or Permo-Carboniferous, as found in 

 Westmorland county, has also been estimated (by Ells) as about 1,000 

 feet, and this is not found in any part of Albert county. It may once 

 have been there, as also later beds of Mesozoic or even Cenozoic origin, 

 and have been removed by erosion ; but making all reasonable allowance 

 for this, it seems improbable that more than 3,000 feet of sediments 

 ever lay above the gypsimi deposits, and it is a question whether this 

 would have led to any appreciable rise of temperature in the beds thus 

 buried. On the other liand, it is kmown that the temperature at which 



