APPENDIX. 



Sib, — In your issuo of Cbristmas morning 

 appeared a letiber from Mr. Tyrrell of the 

 Ge il'gioal Survey crioiciziop my Ipcture on 

 the "Oldest Geology of the Rid River and 

 Assiniboiue Valleys." I have not until the 

 present time had an opportunity of noticing 

 it. With your porniiasion I shall quote the 

 various cricicisms one by one, that none may 

 be omitted. 



1. Mr, Tyrrell says : " The original 

 Arcbastn continental nucleus, spoken of as 

 the 'Liurentiau Island,' extends southward 

 into Minnesota, Wiaconsio, Michigan and 

 New Yoik, and therefore Caaada should not 

 be said to own the vi^bole ot this Laurencian 

 Island, but rather the greater part ot it. The 

 use of the term L*urentiian, instead of 

 Arcbsem. to include boiib Ahe Laurentian and 

 Huronian, is not corr^'ct, any more than it 

 would be correct t j group both men and horses 

 as horses. Liurentian and Huronian were 

 names applied by Sir William Logan to 

 separate geological groups or systems, and as 

 they have not been shown to be the same the 

 one named cannot be used to include them 

 both without caus-ing the utmost confusion." 



The use of Laurentian instead of Archaean 

 was simply to prevent confusion in a popular 

 discu^ion of the subject. I said disninctly as 

 follows : "We have preferred to use the 

 well known term Laurentian rather than 

 Arcbsean which some are now employing to 

 include both Laurentian and Huronian." The 

 terms. "Laurentiian island" and "Laurentian 

 lakes" have now become well known, indud 

 ing as every one ktiows the Huronian. The 

 distinciiou between Laurentian and 

 Huronian is not easily drawn. Prof. 

 Chapman (p*ge 298) says : " The 

 stratigraph'cil relations of twos-^ries, Lauren- 

 tian and Huronian have not yet been clearly 

 mideou". The mneral characteristics and 

 especially the presence of conglomerates hold- 

 ing gneit-soii and other fragments lead un- 

 doubtedly to the conclusion that the Huron- 

 ian beds are of later formation than the 

 Laurentian, bat as pointed out by Dr. 

 Selwyn, the Huronian appear m many places 

 to pass under the latter." lo is well known 

 that members of the geological stafiE form the 

 opinion tbat the Laurentian series are not 

 metamorphic sedim-ntary rocks, and their 

 relation to nhe Huronian is verv uncertain. 

 How absurd it is then to be dogmatic, the 

 more that it has been fourd necessary to 

 invent the col irless word "Archfea" to in- 

 clude the Laurentian and Huronian. As to 

 theexentof the "Laurenti.n island" the 

 portion of tne Laurentian uncovered by Pal- 

 Ee izoic which in outside of Oanad k is utterly 

 trifling c impared with the vast area within 

 our borders. 



2. Mr, Tyrrell says ; "The iron ore on 

 Lake Winniijeg does not occur in "Cam- 

 brian" rocks, but, as has been pointed out by 

 the writer several tim?8, in the highly altered 

 schists of the Huronian system. There is no 

 known natural outcrop of "Cambrian" rocks 

 in Manitoba, and the only record of this sys- 

 tem in the province is in Dr. Dawson's paper 

 on the boring at Rosenfeld where he corel- 



lates the lowes*) 110 feet of his section with 

 the Lower Magnesiam Limestone or Calci- 

 ferous, adding a (?) to indicate a certain 

 amount of dcubt in the correctness of the 

 detproiination. " 



Here Cambiian is u«d to mean the lowest 

 of what were formerly called Silurian, and 

 must now be admittt d to ba at least Oarapro- 

 Silurian. Dr. Dawson is correct in identify- 

 ing the rocks immediately above the Lauran- 

 tian at RosenfeJd ss C*loiferous, which is 

 Cambrian. As in the sase of the Quebec 

 rockp of Eastern Canada, it is difficult 

 to separate chalk v and Calclferous, 

 and especially in Manitoba is it diffi. 

 cult to get a horizon corresponding 

 exactly with that of Ontario. As to the iron 

 bearing rates my statement was that they "lie 

 near the base of the Cambrian," lie on the 

 Laurentian island of which I had been speak- 

 ing, very near the point of union of the Palae- 

 ozoic and underlying rocks. 



3. Mr. Tyrrell says : "Possib'y the most 

 unfortunate sentence in the whole paper is the 

 following : "L^ke Winnipeg is now definitely 

 known to be a broad trougd hollowed out by 

 glacial action, on the east shore consisting of 

 the hard granite and conglomerate of the Laur- 

 entian, and on the west of its lower rocks of 

 the CalciferouB, and probably Potsdam series, 

 now classed as Canadian rocKs lying upon the 

 Laurentian, 



Lake Winnipeg is mt definitely known to 

 have been hollowed out by glacial action. It 

 is much more probable that it is an old pie- 

 glaoial river valley, of the general characcer of 

 that of the Missisippi of the piesent day, with 

 its northern end blocked by drift and alluvial 

 deposits, or a depression has been formed in 

 the bottom of this old valley by movements of 

 the earth's crust ; evidence of theee crusted 

 warpmgs beiogseen in the high beaches along 

 the foot of the Manitoba escarpment. On the 

 easo shore of Lake Winnipeg there is no "con- 

 glomerate" known in the Laurentian, and in 

 fact it is more or less douboful whether there 

 is conglomerate anywhere in the Laurentian. 

 On the west shore no "Calciferous" or "Pots- 

 dam" is known, and there is no reason to suo- 

 pose that there are any pa'se >zoic rocks in 

 that vicinity below the So. Peter's sandstone 

 (chazy) which is there found resting directly 

 on the arcbsean." 



The last first. After the explanation m re^ 

 gard to Laurentian it seems mere trifling to 

 deny the presence of cODglomprates. Prof. 

 Chapman (page 297) says : "The Huronian 

 representatives altbough di»titict> enough in 

 their entirety, closely re^^emble in many cast s 

 the Laurentian rocks of the distric, and can 

 not always be readily seperate fri m them. As 

 a rule, however, the texture is less rryst'Ume 

 or less granitoiQ»lj and slaty or semi-crystal 

 line conglomerates appear among them." Mr. 

 Tyrrell seems to especially object to Lake 

 Winnipeg being so decidedly put down as 

 hollowed out by glacial action. In my lec- 

 ture of last year I had occasion to point out 

 the distinguished service ' in geologizing 

 Manitoba, performed by Prof. Upham, of 

 Boston. So completely did Prof. XJpham's 



