6l6 ALFRED W. G. WILSON 



of the British Association, at the Toronto meeting in 1897, men- 

 tioned, in passing, that the topographic features of the Archaean 

 areas of North America were those of a peneplain. During the 

 past seven summers the writer has had the opportunity of study- 

 ing in more or less detail considerable areas around the southern 

 portion of this Archaean region extending from Lake Champlain 

 in the east to the Hudson Bay divide in central Keewatin. In 

 a paper published two years ago (41)' attention was drawn 

 to some of the geographic features of the southern margin of 

 the Archaean belt within central Ontario. In the present paper, 

 with the aid of the numerous accounts of travels and reports of 

 explorations in various parts of these Archaean regions, these 

 studies have been extended to the greater areas of central and 

 eastern Canada 



The purpose of the present paper is, primarily, to draw atten- 

 tion to the physiographic unit, the Laurentian Peneplain,^ and to 

 present a brief picture of its more salient features ; and, secondly, 

 to outline a few of the almost endless variety of geologic and 

 geographic problems which the Canadian shield presents. Many 

 of these problems, in the present state of our knowledge of the 

 vast area here under discussion, are insolvable ; many perhaps 

 will never be solved ; but none the less it is interesting to review 

 the work already done and to consider that which lies before us. 



' The number refers to the article listed with corresponding number at the end of 

 this paper. A following number indicates the page reference to the article in 

 question. 



^The adjective " Laurentian " is here applied to this, the largest peneplain devel- 

 oped in Canada, to distinguish this topographic unit from others of a similar type 

 also found in Canada or in the adjacent parts of the United States. For example, we 

 have the Atlantic Coast Peneplain, parts of which, under the title of the New England 

 Peneplain, and the Acadian Peneplain have been described by Davis and Daly 

 respectively ; the Tertiary Peneplain of British Columbia has been briefly referred to 

 by Dr. Dawson, and the Peneplain of the Yukon basin has recently been described b}^ 

 H. C. Spencer, G. S. A., May, 1903. The relations of these minor plains to the 

 greater area here under discussion are not yet definitely established. As will 

 be shown in the succeeding paragraphs, the Laurentian Peneplain itself is not a single 

 plain, but rather is made up of a series of facets intersecting at very low angles, three 

 of which are distinguishable south of the main divide, so that there are probably at 

 least five facets, and perhaps more. It has not been deemed advisable at present to 

 suggest names for these facets. 



