382 A. WINCHELL — RESULTS OF Ai:< '11 KAN STUDIES. 



This remarkable and important formation presents graduations in many 

 directions from the typical state, but the scope of this paper permits do more 

 than a mere enumeration : 1. [t graduates into Blate-colored argillite, both 

 along the strike and across it. 2. It often develops whitish, obscurely out- 

 lined crystals of feldspar. These are found in all stages of development from 

 incipient visibility onward. This condition I have called " porphyrel." •">. 

 The formation sometimes contains distinctly outlined, rounded pebbles, 

 especially on the remote anus of Knife lake. The pebbles are sometimes 

 present with the porphyritic structure. 4. The formation also, at times, de- 

 velops grains of quartz, and on the north of < lunflint lake both quartz and 

 feldspar. 5. It graduates into the green schists, which possess exactly the 

 same structure and aspect with a greenish color and diminished translucency. 

 These are the " Kawasachong" or " Kawishiwin " rock, by some regarded as 

 a decayed diabasic rock. ti. It graduates into a gray wackenitic rock with 

 tine granular quartz and feldspar in an argillaceous base. 7. The gray- 

 wackenitic rock assumes a larger proportion of silica and becomes something 

 like hornfels. <s . The formation acquires felsitic matter and becomes agood 

 felsitic schist, and this is quite extensively developed. !•. Through this 

 stage it passes into a silico-diabasic slate, a protean formation truly of 

 which Still much remains to be learned. The essential ingredient is widely dis- 

 seminated in this system of rocks and can often he detected in gneisses and 

 other petrographic conditions not otherwise affiliated with porphyrellite. 

 Thus disseminated I have called it " Kewatin stuff." 



Chraywacke. — As nearly as 1 can judge, very little typical graywacke exists 

 in this Bystem of rocks, hut the name has been much U8< d, and the condition 

 to which it i> applied approximates conformity to the accepted definition. It 

 IS composed of .-mall water-worn grains of quartz and feldspar, imbedded in 



an argillaceous groundmass, with minute mica scales and particles of a black 

 BUb8tance, and generally some silica chemically combined : hut from this 

 Mate i- passes into a siliceous hornfels and a quasi-diabasic state, and, on the 



other hand, graduates into a massive argillitic rock. 



'fie- graywacke holds position next to the crystalline schi-ts, hut it is not 



everywhere present in its place. Next to the gray wacke, as nearly as J have 

 ascertained, come- the poroditic and porphyrellitic formation, with its 

 numerous phases. Next bigher in the scries occur the argillites, with their 

 beteromorphs, and thesericitic Bchists, while near the centre of the folded 

 synclinal occur the beds of haematite. In a tentative way, therefore, I would 

 arrange the members of the system of semi-crystalline rock- in the following 

 manner i 



I. Bericitic Bchists inclosing beds of hsematite. 



.;. Argillites and tin- include. 1 Ogishke-rauncie conglomerate, with len- 

 ticular masses of dolomite. 



