No. 4.] CHALMERS — SURFACE GEOLOGY. 209 



or occasionally in beds of a few feet in thickness sufficiently pure 

 for brickmaking. Along the banks of rivers they form terraces. 

 These terraces are u conspicuous feature of the scenery on the 

 Upsalquitch River and upper Restigouche, but nowhere in our 

 Province are they exhibited on such a grand scale as along the 

 upper St. John between Fredericton and Grand Falls. The 

 material of the highest of these terraces having a flat summit 

 seems to be chiefly sand and gravel, and has a close resem- 

 blance to that of the kames. This upper terrace marks the 

 highest continuous flood plain of the river at the close or imme- 

 diately subsequent to the melting of the ice-sheet of the glacial 

 epoch. The lower terraces (there are generally three or more) 

 have been formed by erosion of the upper or all other terraces 

 of a higher level through the action of the river. And owing to 

 the diminished volume of water as well as to other causes the 

 materials composing these lower terraces are usually finer, with 

 greater quantities of sand varying to loam or clay in places where 

 the river valleys are wide and the current slow enough to permit 

 quiet deposition of sediment. An elevatory movement of the land 

 is not necessary to the formation of river terraces which are beyond 

 the reach of the sea, although by increasing the speed of the cur- 

 rents it may give the rivers greater erosive power. Terrace-making 

 is still going on along our river valleys though apparently at a 

 greatly reduced rate. 



This portion of the stratified deposits, that is to say, the 

 upper terraces, or remnants of the highest flood plains of our 

 rivers, has, as already stated, a marked lithological resemblance 

 to the kame deposits and is obviously related to them in origin. 

 The larger boulders often found in the kames do not, however, 

 occur in the terraces. Besides the latter contain clayey strata 

 sometimes near the bottom, not met with in the Kames. But 

 the character of the earth, gravel and stones composing them, 

 their structural arrangement, as well as their height above the 

 present water courses are striking points of similarity, and indi- 

 cate deposition also from great floods which swept down these 

 river valleys immediately after the retreat of the ice-sheet, — floods 

 so immense as to be out of all proportion to the present streams. 

 What the exact relations are between these river gravels and the 

 kames, however, is a question demanding closer investigation 

 than I have been able to give to it ; but evidently the two forma- 

 tions will have to be studied together. 

 Vol. X. o No. 4. 



