THK SUCCKSSIOX OF DKI'OSITS. 45 



other following;' the uciicnil Ireiul ot' the St. Liiwrcin'o 

 Viilley. Tlu'. houlder-cliiy wliich rests <»n these striated 

 surfiiees is it dark-cdloinctl till, full of Laureiitiaii 

 boulders, aud holding Lrdii (//aria/ is, and also Uiyozoa 

 cliu'duii: to some of the boulders. In aseendinif the 

 Murray IJay ri\-er, we lind these Imulder-heds surmounted 

 by very thieU stratitied elays, with marine shells, whieh 

 extend upward to an elevation of ahout 800 feet, when 

 they give plaee to loose lioulders and unstratitied di'ift. 

 About this elevati(»n, the laminated elays meet a ridge of 

 drift like a moraine, crossing the valley, whieh forms the 

 barrier of a small lake, I'etite Lae, and a second similar 

 barrier separates this from (Iraiul Lac. If the valley of 

 Murrav I'mv river was occupied with a y,laeier descending 



1/1/ I r^ o 



from the Laurent ian hills inland, whieh are probably here 

 l>,000 to 4,000 feet high, this glacier or large detached 

 masses pushed fiom its foot, must ha\e at one time 

 extentled (piite to the border of tlu; St. Lnwi'ence, aiul at 

 another must ha\'e terminated al the borders of the two 

 lakes above nu'ntioned. 



On a still larger scale the X.W. and S.K striation 

 appears in tiie \alley of the Ottawii, and farther west 

 between the head of lake Ontario and lake Huron, in the 

 valleys descending from the Laurent ian ])lateau. Here it 

 may be ascribed in jtart to general ice-laden currents 

 from the norlh-west, and in ])art to ])ortions of the gi'eat 

 Laurentide gl.icier. 



A most important ol)servation bearing on this subject 

 appears in the Report of ^fr. IJ. I'>ell, in the region of 

 lake Nipigon, north of lake Superior. He observed there 

 the prevailing south-west striation, but with a more 

 westerly trend than usual, ("rossing this, however, there 

 was a southerly aud S.K. set of striae which were observed 



