272 [Oct. 184T. 



" The gypsum of Nova Scotia has attracted considerable attention since Mr. 

 Lyell published his reasons for supposing it to be older than had been previously 

 supposed, and you will find much matter relating to your inquiries, in papers 

 by Mr. Lyell, Mr. Brown of Sidney, and myself, published, within the last few 

 years, by the Geological Society of London. I do not, therefore, profess, in this 

 letter, to state much that is new, but merely to give you a general view of the 

 appearances I have observed, and the conclusions deducible from them. 



The great workable deposites of gypsum are all contained in the carboniferous 

 system, and most of them in its lower part. The new red sandstone contains 

 only small veins and thin layers of gypsum, of no economical importance. For 

 proof of this, I may refer you to the papers above mentioned, and to that on 

 the new red sandstone, which I hope will be published in the course of this year. 



The great masses of gypsum quarried in this Province, are the outcropping 

 edges of true beds, apparently as continuous as those of the limestone associated 

 with them, though perhaps not so much so as the accompanying sandstone and 

 shale. These beds are, however, often of great thickness, and this, together 

 with the tendency of their surfaces to be worn into " pits," their association 

 with soft marls and sandstones easily removed by denudation, and the disturb- 

 ances to which our carboniferous strata have been subjected, often prevent their 

 arrangement from being distinctly seen. In the following places, however, it 

 is very evident : 



At Ogden's Point, near Antigonish, the descending order, seen in the coast 

 section, is as follows : 



1. White gypsum, fine grained and rather hard, in thick ) Aggregate 

 laminae, and with minute crystals of carbonate of lime. > thickness 



2. Reddish gypsum, large grained foliated. ) over 100 feet. 



3. Alternations of thin beds of gypsum and of grey earthy limestone. 



4. Grey limestone, laminated and brecciated, a thick bed. 



5. Reddish sandstones and shales. 



The dip of these beds is S. S. E. 25, and the lamination or subordinate bed- 

 ding of the upper bed of gypsum, coincides with this dip. The beds can be 

 traced inland for several miles ; the outcrop of the gypsum running parallel 

 to that of the other beds. 



A section somewhat similar to the above, occurs at De Bert river, but there 

 the limestone, which is fossiliferous, does not alternate with the gypsum at 

 their junction ; the gypsum is, however, evidently a bed superimposed on 

 the limestone. 



Two of the smaller beds near the mouth of the Shubenacadie river, afford 

 good illustrations of the bedding of the gypsum. The first is a bed of black 

 gypsum, on the west side of the river. It is 12 feet thick, and is included in 

 beds of reddish sandstone, a layer of which separates the gypsum into two 

 portions. In this case the contrast between the color of the red sandstone and 

 that of the gypsum, apparently colored by coaly or bituminous matter, is very 

 striking. The other instance occurs on the east side of the river, at the south- 

 ern extremity of the bay, named the " Bend." It is a bed of whitish anhy- 

 drite, with some common gypsum in its upper part, regularly interstratified 

 with reddish sandstones. Near this bed the red sandstones are traversed by 

 a network of very narrow veins of fibrous gypsum. 



