[bailey] gypsum deposits OF NEW BRUNSWICK 9 



the view is open to the same objections as in the case of the theory 

 first referred to. 



Botli of the above views fail to talve any account of the coexistence 

 and intimate association of gypsum and anhydrite. 



(3) Derivation by precipitation from salt ivater in shallow basins. 

 This is the view now generally taken as regards the original deposits 

 of which the plaster beds are the present representatives, and finds 

 strong support in the oljsorvatious made in connection with the residues 

 of such inland seas as the Great Salt Lake of Utah, and the more ancient 

 and more extensive basins known as Lakes Bonneville and Lahontan. 

 It is not, however, believed that the deposits in question, as now found, 

 are necessarily in the same condition as when first deposited. For, as 

 has been stated, they consist in part of gypsum and in part of anhydrite, 

 and questions naturally arise as to the relations of these two. Were 

 they deposited coincidently or has the one been derived from the other ? 

 In the latter case, which was the antecedent rock? and what conditions 

 have determined either their separate precipitation or the conversion of 

 the one into the other? 



As favouring the general view that the Acadian deposits of gypsum 

 were produced by precipitation from sea-Avater, a number of facts may 

 be noticed. 



First, the Lower Carboniferous rocks, of which the gypsiferous 

 strata form the upper member, show throughout the district abundant 

 evidences of marine origin, the most conspicuous being their prominently 

 red colour, due to the absence of vegetable matter, the occurrence of 

 salines, the paucit}^ of vegetable remains and the frequent occurrence 

 of limestones cari-ying corals, crinoids and brachiopods. The distribu- 

 tion of these rocks, together with their relations to the present sea 

 level, also indicate that, as regards portions at least of the era, the 

 Provinces of ISTew Brunswick and Nova Scotia were largely if not wholly 

 submerged, deposits of this age in the former province being found 

 upon the summit of Shepody Mountain (900 feet high, and but little 

 removed from the plaster quarries at Hillsboro), at Henr}'- Lake on 

 the summit ridge of the Quaco Hills (SOO? feet), and on the Tobique 

 river, the beds in each case being but little removed from horizontality. 

 Upon the other hand, the character of the beds, containing but little 

 limestone, but abounding in coarse clastic deposits such as sandstones 

 and pebble beds, indicates that with general subsidence, to a depth pro- 

 bably of several thousands of feet, the waters remained shallow 

 and subject to frequent changes both as to distribution and as to depth. 

 Shifting sand bars or sea walls would from time to time enclose basins 

 or lagoons, wherein, as a consequence of isolation, together with ex- 



