SECTION ON THE SOUTH BRANCH. 



381 



half in diameter, and composed of sand. Below this soft 

 stratum there occurs a layer of sandstone (c) about three 

 feet six inches thick, which is broken into an irregular pro- 

 jecting outline by the protrusion of a series of immense 

 concretions of a flat spheroidal form, like that of a lemon 

 slightly compressed parallel to its longest diameter. The 

 concretions vary from three feet to six feet in horizontal 

 dimensions. They are very hard in the centre, and show 

 concentric rings for at least six inches from their outer 

 casing, which is a shell of gypsum, often passing into 

 selenite. Selenite is found in this and lower strata in 



Section on the South Branch of the Saskatchewan, showing layers holding Avicula 

 Linguseformis and Avicula Nebrascana. 



veins and fragments. Some of the concretions thrust out 

 their rounded forms from the face of the cliff, others have 

 been broken off and show their internal structure. A 

 grey sandstone (d) with a slight tinge of green, soft and 

 friable, then occurs for a space of four feet ; it is suc- 

 ceeded by five feet of hard sandstone (e) containing a vast 

 number of cylindrical forms, slightly conical, and showing 



