140 ROYAL SOCIETY OF CANADA 
of the heights or hills reach a much greater altitude than is the case to 
the westward. Much still remains to be done in determining the field 
as well as petrographical relations of the various crystalline rocks of this 
the oldest complex of formations in the Quebec district. At Mont- 
morency Falls, the Falls of Lorette, Cap Tourmente, and the district to 
the north of Quebec and other localities, the Archean may be studied 
to advantage. It is a remarkable fact that no true Laurentian crystal- 
lines occur south-east of the great Appalachian fault in the vicinity of 
Quebec. This is probably due to the manner in which the newer Cam- 
brian and Ordovician formations in that area have been thrust over the 
underlying older floor and the latter buried deeply. 
THE CAMBRIAN SYSTEM. 
The Sillery formation.—This formation consists for the most part of 
coarse sandstones and grits associated with conglomerates, and red, green 
and black slates which are met with along the St. Lawrence front, at 
the quarries of Sillery village, along the Ste. Foye Road, at Cap Rouge, 
Point Levis, and various localities, both to the north and south of the 
St. Lawrence, and on the Island of Orleans. 
The shaly portion of the Sillery is characterized by the presence of 
very few fossil organic remains. On the Chaudière river, a little above 
Quebec, Sillery slates hold Linnarssonia pretiosa, Billings, fragments 
of fossil sponges, algæ, besides a number of graptolites. The Sillery is 
also characterized at times by the presence of bands of limestone con- 
giomerate, and the whole formation is several thousands of feet in thick- 
ness, its exact thickness having not yet been definitely ascertained, the 
accumulation of sand, boulders forming conglomerate bands and sand- 
stones or quartzites being due to local causes and are therefore of vary- 
ing thickness. Many of the walls and fortifications of Quebec are built 
of blocks of Sillery sandstone. 
THE ORDOVICIAN SYSTEM. 
The Levis formation.—Black graptolitic slates, thin limestone bands 
of light gray colour, cream coloured dolomites, limestone conglomerates, 
and occasional ash beds, constitute the strata of the Levis formation 
which succeed the Sillery in ascending order. The fauna entombed in 
the more or less heterogeneous and irregularly distributed sediments of 
this formation has proved to be very abundant and intensely interesting. 
It was from this formation that the late Mr. Billings obtained so many 
types of new and rare species of paleozoic fossils which enabled him to 
reconstruct the fauna of those early Ordovician seas in the manner 
which he did. 

