UNCONFORMITY BETWEEN HURONIAN AND KEWATIAN. 



117 



massive fine-grained and vitreous quartzite above to a compactly silicious 

 slate below. It holds ramifying veins of hematite, from which, in one place, 

 two or three tons have been mined. This member of the system is indicated 

 by the figure 2 in the accompanying diagram, though the examination of it 

 was made at least half a mile back (north) from the lake. About three- 

 quarters of a mile north of the approach of this quartzite to the shore occurs 

 another in a low outcrop, having a dip of about 20°. This is dark bluish 

 gray, very fine-grained, approaching vitreous (number 3 on the diagram). 

 Half a mile beyond is the long, low projecting point of limestone. The ex- 

 ternal aspect of this outcrop is dark and indescribably rough. The forma- 



Upper Slate: CoNeLOMtRATt 



2 3 4 5 



ViTRCous .Quartzite: BluisnVitrcous Quartzite; : Quartzite: 



\\HV. 



£ C /i P I ^ £ R 



£ C H O L A K £ 



;FnDSPATHIC;U«KNOWN 



:quartzitei: 



9 • 10 It 12 13 14 15 



■ Quartzite:,Vitr£;oi.is,Reooish. : Lowej? Slate. Conglomlrates and Slates. 



£ C H O L A X £ 



CAMP NORTH OF £CHO LAKE 



Figure 2.— Section along Echo River and Lake and northward, showing Unconformity of Huronian and 



Kewatian. 



The numbers 1-16 designate regions described in the text. 



tion is intersected by harder laminae, which resist weathering, and project in 

 thin plates one, two or three inches above the general surface. Being con- 

 formable with the bedding, they project at an angle of about 20° with the 

 horizon, but they are grotesquely crumpled in consequence of the plicated 

 condition of the formation. An attempt was made to photograph this sur- 

 face (see cut, figure 3). The limestone weathers umber brown ; but fresh 

 surfaces are bluish gray and exceedingly fine grained, sometimes marked 

 by delicate bands of harder texture and diflferent color, but not generally 

 brought out except by weathering. The point on the opposite side of the 

 lake is similarly characterized. Tow^ard the west the limestone rises in a 

 high blufi*-faced hill, which pursues a devious course as far as Garden river, 



XVIII— Bull. Geol. Soc. Am., Vol. 2, 1890. 



