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Monday, May 3, 1847. 

 Very Rev. PRINCIPAL LEE, V.P., in the Chair. 



The following Communications were read": — 

 1. On the Boulder Formation and Superficial Deposits of 

 Nova Scotia. By J. W. Dawson, Esq. Communicated 

 by Dr Gregory. 



In this paper the author, describes \st, the geological position of 

 the gypsum deposits. The gypsum beds of Nova Scotia all belong 

 to the carboniferous system. No gypsum occurs in older formations, 

 and in the overlying new red, only slender veins and small nodules 

 are found. The gypsum characterises the lower members of the 

 carboniferous series, underlying the productive coal measures. The 

 associated rocks are red sandstones and clays, with very few fossil 

 plants, and thick beds of limestone abounding in marine shells. In 

 the only well ascertained instance of gypsum occurring above the 

 coal measures, it is accompanied by limestone with some of the same 

 shells. The gypsum forms regular conformable beds sometimes 100 

 feet thick. They are much fractured and difficult to trace from the 

 wooded state of the country ; but one thick bed was traced by the 

 author for ten miles. 



The beds or gypsum often rest on, or are overlaid by, limestone, 

 and these rocks sometimes pass into one another, as at Ogden's Point 

 and Wallace Harbour. In other cases the gypsum is embedded in 

 marly sands and clays, or in reddish grey and purple sandstone ; but 

 limestone is never far distant in ascending or descending order. 



2d, Its characters. The gypsum is remarkably pure and usually 

 white. This purity, according to the author, indicates its chemical 

 origin, as distinguished from the detrital character of the associated 

 beds. It is also highly crystalline, being often large grained and dis- 

 tinct ; but usually lamellar ; the plates of selenite having occasionally 

 a stellar arrangement. The beds rai-ely exhibit a fibrous structui-e, 

 which is chiefly seen in the narrow veins ; but they often shew a 

 laminated structure, parallel to the beds. 



3d, The foreign matters contained in the gypsum. These are, 1, 

 grains of quartzose sand ; 2, coaly or bituminous matter. Near the 

 mouth of the Shubenacadie is a bed of black gypsum, included in 

 red sandstone, without a trace of bitumen ; 3, crystals and fragments 

 of carbonate of lime, and small grains of raagnesian limestone ; 4, 

 red oxide of iron, especially in the veins ; 5, anhydrite. 



The anhydi-ite is usually associated with the common variety. 



