DISCORDANCES IN DIP AND STRIKE. 103 



the river, as far as Ottertail. The same is true north frora Ottertail across 

 the quartzite ridges. The slate conglomerate met in this direction, two miles 

 south of Murray's Corners, has a dip of 40° toward south 30° west. This is 

 certainly the upper slate conglomerate, since it immediately underlies the 

 lower, or red, quartzite. Logan's map also locates the upper slate conglom- 

 erate near here, though its southern border is laid down a mile and a half 

 further north. Two miles north of this is Murray's hill, about 170 feet high, 

 and formed of a slate conglomerate of a somewhat different character, and 

 having a dip southward of 78°. Here is a discordance in dip and strike 

 with the first slate conglomerate ; and though this is embraced by Logan in 

 the coloration of the upper slate conglomerate, we feel confident that it is 

 the lower — an opinion apparently sustained by the discordances noted. Be- 

 tween the first occurrence and the second is space for a normal thickness of 

 5,745 feet, basing the calculation on a dip of 40° in a' direction making an 

 angle of 30° with the meridian. This normal thickness is sufficient for the 

 upper slate conglomerate and the underlying limestone, or felsitic quartzite 

 and limestone, known to be present in some other places. Thus the top of 

 the upper slate conglomerate makes an angle of 38° with the top of the lower 

 slate conglomerate two miles distant, and the two strikes are at an angle of 

 about 30° with each other. 



It may be permitted to mention here also an observation made * near the 

 Vermilion river, where crossed by the Sudbury branch of the Canadian 

 Pacific railway. Here is a very dark compact, slaty rock, quite arenaceous, 

 with shining particles, looking micaceous or graphitic, and having a dip of 

 45° in a direction a little east of south. This rests on a different schist, 

 having a different dip. Opportunity did not permit complete observations 

 here, but it was noted that the two formations have strikes making an angle 

 of about 40° with each other. This occurrence and others of the kind were 

 noted by different members of the party. Though nothing could be con- 

 cluded from observations so incomplete, they tend to confirm the position 

 here maintained, that an older system of rocks, with steep dips, is partially 

 covered, in the region north of Lake Huron, by a newer formation, with 

 dips less inclined to the plane of the horizon. 



Evidence from Independent Ohservation. — An independent version of these 

 observations has just come into our hands. Professor N. H. Winchell, one 

 of the Huronian excursionists, says : f 



"At the crossing of the Vermilion river is a repetition of the falls, ridges and rapids 

 seen at Thompson, Minnesota, the whole being manifestly of the same age, and sup- 

 posed to belong to the Animike or true Huronian. The dip of the slates is 45° toward 



* During the "Huronian Excursion" from Toronto, generously arranged by Dr. Selwyn, of the 

 Canadian Geological Survey, for the benefit of the geological section of the Arnerican Association, 

 September 4-5, 1889. 



tin Eighteenth Annual Report, Minn. Geol. Survey (p. 54), from advance sheets of which the 

 citations are made. 



