100 THE CANADIAN NATURALIST. [Vol. 



IX 



furnish a paying mine ; their small percentage of copper is com- 

 bined with sulphur ; amygdaloids are comparatively rare, and 

 seldom contain anything else than calcspar ; these beds are in- 

 truded amongst or interstratified with slates, shales and limestones; 

 contorted strata are often observable, and a belt of fossiliferous 

 rocks adjoins them to the north west. On Lake Superior the 

 supposed identical rocks are distinctly granular, seldom schistose, 

 frequently support remunerative mines on their native copper ; 

 amygdaloids are abundant, and filled with native copper, calcspar, 

 quartz, zeolitic and other minerals in profusion ; they have the 

 form mostly of overflows, not intrusions, and they are associated 

 with sandstones and the coarsest of conglomerates, shewing por- 

 phyritic, Laurentian and Huronian boulders ; the strata are not 

 contorted, have a regular dip in one direction, are innocent of 

 fossils themselves, and are far distant from any formations con- 

 taining them. 



3. Mr. Selwyn disputes Dr. Hunt's contention that the Kewee- 

 nian series overlies the Huronian unconformably, and cites U. S. 

 authorities against this view. Preferable to these would have 

 have been Mr. Selwyn's own testimony as regards this question, 

 and it is to be regretted that he has not yet devoted much time 

 to the Lake Superior region. When any one wanders along a sea- 

 beach, with overhanging cliffs on one hand, and observes on the 

 other the water-worn boulders, pebbles and sand derived from it, 

 he feels pretty certain that the shingle is unconformable to the 

 cliffs. So, on Lake Superior, along its eastern shore, between 

 Sault Ste. Marie and Michipicoten, there are frequently found, 

 betwixt the water and the Huronian or Laurentian hills, narrow 

 strips or patches of the rocks of the Upper group, which often jut 

 out as small islands into the lake, and doubtless extend out great 

 distances beneath its waters. Such limited strips of these rocks 

 are found, for instance, skirting the base of Gros Cap, along the 

 south shore of Bachewahnung Bay and at Cape Gargantua. 

 Among these rocks the conglomerates are full of Huronian debris, 

 and in those of Bachewahnung Bay boulders may be observed 

 of red jasper conglomerate, the characteristic rock of the typical 

 Huronian. If this, and the position of the Maimanse series, uncon- 

 nected with any Huronian background, be not sufficient, I would 

 mention the attitude of the rocks of Michipicoten Island. Here 

 the strata, igneous as well as sedimentary, have an average strike 

 of N. 68^ E. and a dip of 25^ southeastward. The nearest Huro 



