448 W. A. Joliuston — Calcareous Sandstone, 



banks and shifting of tlie river channels ; for the material 

 dredged from the bottom of the river is usually water- 

 worn, whereas that dredged from the sand banks is not, 

 and the currents in the channels are too strong to permit 

 of formation of the material. A careful search of the 

 sand banks exposed at low tide failed to reveal any of the 

 sandstone in place. It probably, therefore, forms below 

 the level of low tide but at a depth of only a few feet 

 below that level. It can not possibly be derived from 

 erosion of older formations for no such deposits are 

 being eroded by the river, and it occurs in the seaward 

 part of the Recent delta to which no material larger than 

 fine gravel is being transported by the river. 



The specimens of the material obtained show that it 

 consists in part of sandstone of which the cementing 

 material is calcium carbonate, in part of sandy or silty 

 and shelly limestone, and in part of concretionary lime- 

 stone. A partial analysis of one sample of the material,, 

 made by Mr. R. D. McLellan of the Department of Mines, 

 Canada, gave the following results : 



SiO. 42.01 per cent. 



Fe..03 + A1.0 7.42 " " 



CaO ' 36.04 '' " 



COo 14.40 '' " 



HoO 0.02 '' '' 



Total 99.89 per cent. 



The material of this specimen is composed of sand, 

 grains cemented together by calcium carbonate, which 

 constitutes 50 per cent of the rock. The proportion of 

 lime varies considerably in different specimens, the con- 

 cretion-like specimens being largely composed of lime ; 

 others are composed largely of shells with a mixture of 

 sand and silt cemented by lime. The material is largely 

 calcareous sandstone. It occurs as irregularly shaped 

 masses which are quite consolidated when brought out 

 of the water. Marine shells partly dissolved and frag- 

 ments of wood only slightly altered are nearly always 

 associated with the occurrences and usually form parts of 

 the material. In the vicinity, where the material occurs 

 there is usually an escape of gas which is inflammable and 

 is probably marsh gas. During th'e freshet stage, of the 

 river, (May, June, and July,) the sand banks are covered 

 for the greater part of the time by fresh river water. 

 During the low-water stage sea-water covers the banks 



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