L66 A. (. LAWSON — THE PRE-PALEOZOK SURFACE. 



tad of the Animikie, on the wagon trail about midway between (Jreen point 

 and Wild < roose point. 



At Silver barbor, farther up the north side of Thunder bay, there ia a strip 

 of the Animikie consisting of 1"» to 20 feel of flat Blates and cherty beds, 

 capped by 50 feet of trap, from beneath which on the north, acrossa narrow 

 Btrip of swamp, rises the Archean surface in well-defined rochea moutonnet t. 



Contacts hetween the Nipigon and Older Rocks. — In the vicinity of Loon 

 lake the basal beds of the Nipigon series overlap the northern edge of the 

 Animikie and rest in undisturbed attitudes directly upon the Laurentian. 

 On the north side of Loon lake and eastward to the vicinity of Pearl river 

 the Laurentian rises from beneath the Nipigon sandstones and conglomerates 

 in prominent hummocky hills. These conglomerates are made up very 

 largely of boulders and rounded pebbles of the Laurentian, which are in- 

 distinguishable in general aspect from the more rounded erratics in the 

 glacial drift. 



In the bed of the creek at the tank of Pearl river station a low, rounded 

 hummock of Laurentian gneiss appears from beneath the Nipigon sandstom 

 and at the first rock cut east of the station, 200 or 300 yards distant, the 

 Bandstones may he seen in the vertical section of the cutting, resting upon 

 the -lope of a hummock of Archean schists and dipping away from it to the 

 eas! at an angle of 15°. Here the Bchists are rotted in places, leaving a few 

 harder nuclei or boulders of disintegration in situ. Haifa mile farther 

 east along the track prominent, lumpy knobs of Laurentian rise above the 

 level of the Nipigon Bandstones to a height of over 100 feet, and on the east 

 side of these, in a rock cut of the railway, the -andstones may he seen repos- 

 ing directly upon their slopes, a- an outlying patch. 



About ten miles east of Nipigon, on the ( !anadian Pacific railway,there i- a 

 prominenl bluff of Nipigon sandstone, capped with a thick sheet of verti- 

 cally columnar trap, the whole presenting escarped faces which rise mi three 

 sides precipitously for several hundred feel above the hummocky plain of 

 Laurentian rocks upon which it rests. The bare Laurentian basement is 

 traceable up to the talus at the bases of the cliffs, and presents the appear- 

 and t passing under the column of superincumbent strata in the same 



hummocky condition as that which it has beyond the dill'-. 



Aboul ten miles east of Mazokama station on the Canadian Pacific rail- 

 way ;t prominent point runs out into the lake, the core of which consists of 

 hummocky Laurentian gneiss, and the outer margin or shore of superim- 

 posed Nipigon Bandstones and conglomerates. Here again the Laurentian 

 appear- to pass under the Nipigon with its characteristically hummocky sur- 

 face, the country being well bared ; and thai it does bo is proved beyond 

 question by the fact thai scattered over the Laurentian ana, away from the 

 edge of the Nipigon rocks, there are numerous outlying patches of the basal 



