[WILSON] PALEOZOIC TO THE PRE-CAMBRIAX 17 



hence away from the Laurentian highlands, and it is evidently on this 

 account that the various formations outcrop successively from north 

 to south in belts trending parallel to the margins of the adjoining 

 Pre-Cambrian uplands. The total thickness of strata represented in 

 this Palœozoic belt is probably not less than 3,000 feet.^ 



The second subdivision in the Palaeozoic border zone includes 

 the district in southeastern Ontario and the adjacent portions of 

 Quebec and New York state that lie between the Laurentian high- 

 lands on the north and the Adirondack mountains on the south. 

 Throughout most of this territory the predominating formation 

 exposed at the surface is the Trenton which as shown on the map of 

 Canada prepared by Logan and on the Grenville and Cornwall sheets 

 prepared by Ells, outcrops broadly in the region lying between the 

 lower Ottawa and St. Lawnrence rivers. Around this central area 

 of Trenton the older Palaeozoic formations, the Black River, the 

 Chazy, the Beekmantown, and the Potsdam outcrop in successive 

 belts so that except where the relationships have been obscured by 

 faulting the structure is that of a broad syncline.- In the region ad- 

 joining the lower Ottawa river adjacent to Ottawa and eastward, 

 however, a faulted zone occurs in association with which areas of shale 

 and limestone belonging to the Utica, the Lorraine and the Richmond 

 formations have been down-faulted into juxtaposition with older 

 forrnations the maximum displacement so far recorded being that 

 adjacent to the Hull and Gloucester fault along which at one point 

 the Richmond shale adjoins the Beekmantown dolomite. The dis- 

 placement in this localit}^ is therefore equal to the thickness of the 

 strata intervening between the Beekmantown and the Richmond, or 

 approximately 1,600 feet.^ The maximum thickness of the Palaeozoic 

 represented in this faulted belt is estimated to be 1,900 feet; the 

 maximum thickness of strata present throughout the region outside 

 the faulted zone where the Trenton limestone is the uppermost forma- 

 tion on the other hand is approximately 1,200 feet. 



The district included in the Ottawa valley to the west of Ottawa 

 which forms the third subdivision of the Palaeozoic border belt, 



1 Ami. H. M. and Adams, F. D.. Ann. Rep. Geol. Surv. Can., Vol. XIV, 1901, 

 Pt. O, pp. 25-29. 



* Ells, R. W., the Physical Features and Geology of the Palaeozoic Basin, Be- 

 tween the Lower Ottawa and St. Lawrence Rivers, Proc. and Trans. Royal Soc. 

 Can., 2nd series. Vol. VI, 1900, pp. 99-120. 



'Ami. H. M., On the Geology of the Principal Cities in Eastern Canada, Proc. 

 and Trans., Royal Soc. Can., 2nd series. Vol. VI, 1900, p. 129. Foerste, A.F., 

 Upper Ordivician formations in Ontario and Quebec, Mem. 83 Geol. Surv., Dept of 

 Mines Can., 1919. From information regarding drilling records in the Ottawa 

 district supplied the writer by E. D. Ingall. 



Sec. IV, Sig. 2 



