174 The Ottawa Naturalist. [December 



series, resting upon the Fundamental Gneiss. In this no trace 

 of sedimentation is now apparent ; while in the Grenville 

 series the originally clastic character is clearly recognized 

 in several of its members. The rocks of the Grenville 

 series have been worked out along their westward development 

 and have been found in this direction to include the series 

 named by Vennor, the Hastings, which is apparently the same 

 as the Grenville, under different conditions as regards alteration 

 and local development ; the limestones of the Hastings series 

 being frequently less altered, and associated with micaceous and 

 other schists, along with beds of slate and true conglomerates. 



East of the St. Lawrence. 



The great problems as to the structure of the Quebec 

 Series or Group which have been prominent for nearly fifty 

 years have also been settled, at least to the satisfaction of those 

 most familiar with all the aspects oi the question. The 

 crystalline series ol the Sutton Mountain, at one time regarded 

 as the newest member of the Group has been separated and 

 placed m the pre-Cambrian division, and are presumably of 

 Huronian age, since it has been found that these rocks underlie 

 the lowest fossiliferous Cambrian sediments. Above these crys- 

 talline rocks there is a very considerable thickness of strata 

 which represent the Cambrian and which have been locally 

 assigned to the lower Sillery formation, for the sake of descrip- 

 tion ; and these rocks contain, at many points, organic remains 

 such as trilobites, graptolites, etc., which have a marked Cam- 

 brian aspect. The fossiliferous beds of the upper Sillery and 

 Levis have been carefully searched and studied, stratigraphically, 

 and it has been conclusively shewn that the Levis is the upper 

 member and overlies the upper Sillery; and, that in fact the Sil- 

 lery is the downward prolongation of the Levis without manifest 

 break, except that the fossil contents become less abundant in 

 the upper Sillery, as in the case of the passage of the Calciferous 

 of the Ottawa Basin downward into the Potsdam sandstone, 

 where there is also no marked line of separation, except in the 

 change of character in the composition of the strata. There is 

 however a marked break between the slates and sandstones of 

 the upper Sillery and the limestones and slates of the lower 

 Sillery ; since in connection with heavy faults between the two 

 series there are thick beds of limestone conglomerate at the base 

 of the upper Sillery, abounding in pebbles of limestone 

 which contain numerous specimens of Olenelhis Thompsoni, and 



