196 C. K. LEITH 



like forms on the weathered surfaces, are to be seen about Moose Lake, 

 and southeast to Snowbank Lake, about Disappointment Lake, Keke- 

 quabic Lake, and eastward to Zeta Lake. 



3. Granitic intrusion, chiefly represented by the granite of Sag- 

 anaga Lake, where the Upper Keewatin lies unconformably upon it. It 

 is also seen a little west of Ely and on the Kawishiwi River. At West 

 Seagull Lake this granite cuts older greenstones and green schists. 



4. Lower Keewatin or Kawishiwin. — This is mainly a greenstone 

 formation, both massive and fragmental, and constitutes the oldest for- 

 mation in the state. When stratified it consists of basic tuffs, agglom- 

 erates, and green stratified schists and greenwackes. It contains the 

 banded jaspylites and iron ores at Vermilion Lake. Where cut by 

 granite and porphyry (1), these rocks are converted to mica-schist and 

 banded gneiss. 



Unconformably above all these is the Animikie formation, of 

 Taconic age, the base of the Paleozoic. 



Nos. (1), (2) and (3), above, are paralleled in Finland by similar 

 rocks in similar order, as described by Sederholm. Rocks correspond- 

 ing to No. (4), the Lower Keewatin, seem to be wanting, or are seen 

 only as inclusions in the next younger granite. 



It is probable that the divisions above detailed for Minnesota and 

 Finland are wholly embraced in the lower division of the Canadian 

 Laurentian, i. <?., in the Ottawa gneiss, and that they have not yet been 

 noted in Canada. The fundamental gneiss of Canada is, therefore, 

 not the bottom of the geological series, but is largely a sedimentary 

 series, derived from an older series, this older series being in part at 

 least a greenstone, as indicated by the stratigraphic succession in Min- 

 nesota. 



Comments. — In the above papers Winched has modified his ideas 

 from time to time with reference to the general succession of the pre- 

 Cambrian rocks of northeastern Minnesota, and it may be well briefly 

 to summarize what appear to be his latest conclusions. The succession 

 from the base upward is as follows: (1) greenstone, both massive and 

 fragmental, called the Lower Keewatin ; (2) cutting this is a massive 

 granite, typically developed at Saganaga Lake ; (3) unconformably 

 above the Lower Keewatin is a series of sedimentary rocks, consisting 

 of conglomerates, sericite-schists, quartzose and micaceous schists, gray- 

 wackes, clay-slates, chloritic schists, and porphyroids, called the Upper 

 Keewatin ; (4) granite cutting and metamorphosing all the preceding. 



