204 INDEX TO THE STRATIGEAPHY OF NORTH MIERICA. 



These rocks, both the fossiliferous sediments and the intrusive masses, have been well 

 described in the earlier reports of the Survey." In the first of these, viz, that for 1847, the char- 

 acters of the rocks visible on the line of section between Montreal and Lake Memphremagog are 

 so clearly stated that but little remains to be said on that subject. 



As, however, the relations of certain groups, more particularly the crystalline schists and 

 the red and green slates and sandstones of the Upper Cambrian (Sillery) were not at that time 

 clearly understood, these will call for some remarks on a subsequent page. The general hori- 

 zontality of the measures, except where this is disturbed by the presence of the intrusive masses 

 or dikes, is maintained almost to the vicinity of- the great St. Lawrence and Champlain fault, 

 which, as already described in a former report, extends from the city of Quebec to the foot of the 

 Missisquoi Bay. The fault brings beds of the Trenton formation against the Calciferous and 

 Chazy at Phillipsburg and Stanbridge, and its existence is very evident wherever rock exposures 

 are visible along its line, but as there is a heavy covering of drift over a considerable portion 

 of the country which it traverses, its delineation on the map between exposed points must of 

 necessity be largely conjectural. 



This great fault marks one of the important geological features of the district under dis- 

 cussion, but the amount of displacement occasioned thereby is presumably no greater than that 

 caused by other heavy faults which traverse the country in a northeast to southwest direction 

 and which are seen aS far east as Lake Memphremagog. Not only is this entire area greatly 

 affected by these faults, but extensive crumplings of strata occurred, which have closely involved 

 the rocks of the older or crystalline-schist area with the most recent sediments of the district. 

 Narrow areas of the Cambro-Silurian are seen, which contain fossils but are apparently inter- 

 stratified with the schists; while in some places the formations are so completely overturned that 

 the fossihferous Devonian now underlies the Cambro-Silurian. 



The rocks of the Trenton formation, which underlie the Utica and Hudson River [Normans- 

 kUl horizon — ^Ami] (Lorraine) just described, have also a wide distribution. In the earlier 

 reports of the Geological Survey * certain portions of these rocks were included in the Upper 

 Silurian; these comprise both the black graphitic limestones and associated clay slates. 



Lists of fossils of these Ordovician. terranes are given by Ami in appendices to 

 EUs's reports on the areas covered by the Pembroke, ^° Perth, ^* Montreal/* and 

 Grenville ^^ sheets. 



In that part of the St. Lawrence Valley which lies east of the St. Lawrence- 

 Champlain fault Ordovician rocks occur on both sides of the Sutton Mountain anti- 

 cline. Omitting the Sillery and Levis (described in Chapter III, pp. 131-134), we 

 have here to deal with the limestones and shales of Phillipsburg, Franklin, and Bed- 

 ford, which range along the northwestern base of Sutton Mountain, and the Magog 

 shales, which occur southeast of that anticline in the basin of Lake Memphremagog; 

 also with the Quebec formation of Citadel HUl in the city of Quebec and the Ordo- 

 vician strata which form islands and points along the south shore of the lower, St. 

 Lawrence. 



The limestones and shales of Phillipsburg and Bedford occur between the St. 

 Lawrence-Champlain thrust fault and Sutton Mountain. The thrust fault strikes 

 Lake Champlain at its northeastern extremity, Missisquoi Bay, passing through the 

 village of Phillipsburg. East of it occur rocks assigned by Ells ^^^^ to the " Calcif- 

 erous" and Chazy. Logan's section of the "Calciferous" (divisions A and ,B) has 

 been given in Chapter III (p. 134) . The strata are gray to black dolomites and lime- 

 stones, which according to Ells " shade gradually into the Chazy in the upper part, 



a Logan, W. E., Eept. Progress Geol. Survey Canada, 1847-48, pp. 10-22. Hunt, T. S., idem, 1858, pp. 171-178. 

 Logan, W. E., Geology of Canada, 1863, pp. 205-210. 

 6 Logan, W. E., Geology of Canada, 1863, p. 434. 



