No. 1.] SELWYN — THE QUEBEC GROUP. 25 



Roland Irving writes : the unconformity between the Huronian 

 and the upper copper-bearing rocks " is not certainly proven ^^ 



A very considerable amount of careful investigation and 

 laborious work in the field is yet required before the indicated 

 divisions can be correctly delineated on the map. The two maps 

 exhibited shew respectively the supposed distribution of the old 

 divisions of Levis, Lauzon and Sillery, and that of the new divi- 

 sions (so far as they have been determined), which I now 

 propose to adopt. These latter have at least the advantage of 

 simplicity ; they also obviate the necessity of invoking any of the 

 numerous almost impossibilities in physical and dynamical geo- 

 logy which are required to explain the previous theory of the 

 structure, and they are, moreover, very closely in accord with the 

 views entertained by Professor Hitchcock as regards the general 

 succession of the formations in the adjoining States of New Hamp- 

 shire and Vermont. 



Laurentian. — I shall now make some observations on the 

 results of the recent work of the Survey in unravelling the com- 

 plications of the stratigraphy of the older " crystallines " on the 

 north side of the St. Lawrence Valley. Since 1866. 3Ir. H. G. 

 Vennor, of the Geological Corps, has been occupied in a careful 

 examination of the stratigraphical relations of the Laurentian 

 rocks. His observations, commencing in Hastings county, north 

 of Lake Ontario, have now extended across the Ottawa River, 

 eastward, to Petite Nation and Grenville, embracing a band of 

 country 200 miles in length, with an average breadth of 55-60 

 miles. Throughout this tract of country, Mr. Vennor has fol- 

 lowed and mapped, in all their windings and convolutions, the 

 great series of Laurentian limestone bands first investigated 

 and described by Sir W. E. Logan, in the years from 1853 to 

 1856, more particularly in the Grenville region, and in 1865, by 

 Mr. Macfarlane, in the Hastings region. The results and con- 

 elusions of all these earlier examinations are given in detail in 

 the Geological Survey Reports. And these shew that the classi- 

 fication then adopted by Sir W. E. Logan was regarded by him 

 as provisional. (See Note, p. 93, G. S. R., 1866.) 



Thus, at the commencement of Mr. Vennor's investigation in 

 1866, it was supposed that the limestones and calcareous schists 

 of Tudor and Hastings holding eozoon, together with certain 



* Am. J. of Sc, Vol. XIII, 1877. 



