[WILSON] PALEOZOIC TO THE PRE-CAMBRIAN 23 



to the scarp was a mass of Beekmantown dolomite that outcrops in 

 lot eleven, Range III, Grenville township. This mass outcrops in the 

 bank of a creek and dips to the south away from the Laurentian high- 

 lands at an angle of approximately 35 degrees. Recently, however, Mr. 

 Arthur Lanigan, of Calumet, has drawn the writer's attention to two 

 outcrops of Potsdam sandstone that peep through the talus on the 

 slope of the escarpment in lot 20, Range II, Grenville township. At 

 this point the sandstone is exposed on the hill slope about 100 feet 

 above its base and directly in front of a steep scarp of Pre-Cambrian 

 granite gneiss. The sandstone is the fine-grained normal variety, 

 contains no pebbles of granite gneiss, is much broken, and at one 

 point is intersected by a small east-west fault — the surface of which 

 is polished and striated vertically. The actual contact of the sand- 

 stone and the granite gneiss is not exposed, however. On making a 

 further search for outcrops in this locality it was found that Beekman- 

 town dolomite was present in the banks of a small creek gully situated 

 a few hundred feet to the west of the sandstone outcrops. Here also 

 the dolomite is much broken and terminates abruptly against a scarp 

 of granite gneiss. On the whole, therefore, although the actual fault 

 contact was not observed there is much evidence to indicate that a 

 fault is actually present in this locality. 



As regards the origin of the Eardley escarpment no outcrops of 

 Palaeozoic strata, so far as known to the writer, have been observed in 

 close proximity to its base, and the hypothesis that a fault is present in 

 this locality is based entirely on the general evidence already cited. 



Objections to the hypothesis that the Eardley and Grenville escarpments 



are related in their origin to a through-going fault or are 



parts of a fault-line scarp. 



The data indicating that the Eardley and Grenville escarpments 

 are not related in their origin to a through-going fault have been 

 previously stated and hence may be merely summarized in this con- 

 nection. Among the most important of these data are the following: 



The Eardley and Grenville escarpments are comparable in length 

 and parallel in trend to local faults that intersect the Palaeozoic for- 

 mations along the Ottawa river a few miles farther to the south. 

 They are therefore probably related in their origin to similar local 

 faults and in that case would be entirely separate from one another. 



If the southern border of the Laurentian highlands to the north 

 of the lower Ottawa and St. Lawrence rivers were delimited by a 

 continuous fault this fault would presumably express itself physio- 

 graphically as a continuous fault-line scarp, whereas, except in two 



