634 FRANK D. ADAMS 



cession of strata or whether in it there may be two series of identical 

 petrographical character, intimately associated, and which have been 

 subjected to the same intense and widespread metamorphism. The 

 information hitherto accumulated and bearing on the question may 

 be briefly stated. In the report upon the Haliburton-Bancroft 

 area, by Dr. Barlow and the writer, to which reference has already 

 been made, the occurrence of conglomerates at a few separated points 

 in the southern portion of the area is described and the conclusion is 

 reached that certain of these are probably of epiclastic origin and 

 indicate an unconformity in the series. If two series be present, 

 however, the intense metamorphism and folding has rendered it 

 impossible to delimit them in the area embraced by the report in 

 question. When the international committee representing the 

 geological surveys of the United States and Canada (appointed for 

 the purpose of effecting a correlation of the pre-Cambrian rocks of 

 the Adirondack Mountains, the "Original Laurentian Area" and 

 Eastern Ontario) visited the Madoc district, which lies to the south 

 of the Haliburton-Bancroft area, they examined a conglomerate near 

 the town of Madoc and concluded that it probably represented a 

 break in the pre-Cambrian sedimentary limestone series as there 

 developed. Miller and Knight, who visited the district in the autumn 

 of last year, stated in a short paper which appeared in the Report of 

 the Ontario Bureau of Mines for 1907 (p. 202), and which was after- 

 ward read before the American Geological Society, that "a few days 

 in the field has made the relationship of the sedimentary series quite 

 plain, and the view that the Grenville and Hastings series constitute 

 one series, the former being a more highly altered phase of the latter, 

 is no longer tenable." A careful study extending over many months, 

 however, shows that Logan was quite right and that the comparatively 

 unaltered strata of what he mapped as the Hastings series pass over 

 imperceptibly into the typical Grenville series. What the committee 

 saw, and Messrs. Miller and Knight have substantiated, is that within 

 this unaltered "Hastings series" of Logan, as also probably in the 

 more altered "Grenville" phase of the same rocks, there are two 

 series which are petrographically identical. These series, when worked 

 out, should be distinguished by specific names, as Upper and Lower 

 Grenville, or one may be termed the " Madoc series." Logan's " Hast- 



