LOCAL CHARACTER OF THE CONGLOMERATE. 465 



of limestone, which are also often of large size, hold an abundance of Pots- 

 dam forms, while others have large orthoceratites. The paste of this con- 

 glomerate contains fossils characteristic of the Calciferous formation, and in 

 places it is difficult to distinguish between the matrix and the pebbles them- 

 selves. These conglomerates are generally very local in their development, 

 and frequently form lenticular masses, surrounded by the characteristic Levis 

 shales. Much of the confusion arising from the study of these rocks has 

 been to a large extent due to the neglect in keeping clearly separated the 

 fossils of different horizons — i. e., those obtained from the bowlders and those 

 from the paste. 



The fourth zone of conglomerates is that seen in the city of Quebec. These 

 are associated with the blackish bituminous shales and limestone of the 

 Citadel series, which have been found to contain a large fauna, embracing 

 graptolitic and other forms, presumably of Trenton- Utica age. These rocks 

 of Quebec city were formerly regarded as a portion of the " Quebec group " 

 proper, and the necessity for their separation was pointed out first by Dr. 

 Selwyn in 1877-78. The examination of the fossils from these strata by 

 Professor Lapworth and of more recent collections by Mr. H. M. Ami has 

 confirmed the views then advanced as to their later age, and they may there- 

 fore be considered as a somewhat peculiar development of strata intermediate 

 between the fossiliferous Levis shales and the Hudson River formation. 



The Paleontological Succession. — The evidences already presented from the 

 stratigraphical standpoint as to the lower position of the Sillery formation 

 have been largely confirmed by the most recent determinations of the fossils 

 obtained from many points. The examination of these was entrusted to 

 Professor Charles Lapworth, whose conclusions were stated in a paper read 

 before the Royal Society of Canada in 1886. In this paper Professor Lap- 

 worth clearly recognizes three zones of graptolites, of which the first is 

 styled the Cape Rosier zone, or zone of Dictyonema sociale and Bryograptus, 

 and is regarded by him as representing probably a portion of the Cambrian 

 system. The second, or Ste. Anne zone, or that of PhyUograptus anna, includes 

 the great bulk of the graptolites from the fossiliferous beds of Levis and 

 vicinity. He regards this as newer by a well-marked interval than zone 1, 

 and as representing the base of the Ordovician or Cambro-Silurian system. 

 The third, or Ccenograptus gracilis zone, includes the rocks of Quebec city, the 

 north side of Orleans island and of the shore of the St. Lawrence below the 

 Marsouin river as well as other points, and is typical of a distinctly higher 

 horizon than the last, or probably that of the Trenton-Utica. 



From this evidence it is plain that the fossils of zone 1, already obtained, 

 which include also the Obolella and Lingulce already referred to, and are 

 from a part of the red and green shale series of the Sillery, are assignable 



