) THE CANADIAN NATURALIST. [Vol. viil. 



The composition of the delessite, he gives as follows : 



Silica, 31.78 



Alumina, - 15.47 



Ferrous Ox?de, .... 28.87 



Lime, - ... 9.64 



Magnesia, - 4.37 



Water, - ... 9.87 



The amygdaloid consists of 



Delessite, - - - - - 38.00 



Labradorite, - - - 62.00 



lOO.Od 



100.00 



Among the silicates occurring in the amygdaloids are Epidott % 

 Prehnife, Lavmonite, Anulcite, Datolite, &c. Besides these, 

 Heulandite, Chahazite, ApophyUite, Stilbite, Natrollte, Leon- 

 hardite, Mesolite, &c, are obtained from the fissure veins. 



The conglomerates are principally composed of brown fel- 

 sitic pebbles, often with small imbedded crystals of triclinio 

 feldspars. Occasionally the pebbles are bright flesh red, deriv- 

 ed from minute crystals of feldspar of that color. Sometimes 

 the pebbles are of aniygdaloidal trap. The matrix is generally 

 dark brown having a texture from sub crystalline to almost * 

 compact vitreous mass. In some localities the pebbles contain 

 no free silica, while in others the rocks are almost jispcry. The 

 cement is fine grained, and is either siliceous, chloritic, epidotio, 

 cupriferous particles, or else it consists of the comminuted mater- 

 ial of the pebbles. As noticed by Pumpelly, the aniygdaloidal 

 conglomerates can often be traced over several miles, as the 

 filling of different beds is sometimes uniform over a considerable 

 distance. The felsitic and jaspery pebbles of certain conglome- 

 rates appear to have been derived from Huronian rocks, which 

 were exposed somewhat beyond the limits of the igneous over- 

 flows during the period of time under consideration. 



The sandstones are usually of a brick red color, although some 

 of the beds are light yellowish. The sediments of which these 

 rocks are made up has been principally derived from the material 

 of the conglomerates. The beds have frequently a slaty charac- 

 ter, the argillaceous material being derived from the decomposi- 

 tion of the feldspars. Some of the beds, as at Copper Falls, 

 show their shallow water origin, as they have ripple and raia 

 drop markings, and mud cracks The limits of the sandstone 

 strata are usually well defined, although some of the beds seem 

 to be uuited with the overlying melaphyres, as if the porous sand 



