370 



\. WINCHELL — RESULTS OF A.RCHEAN STUDIES. 



Dr. Lawson remarks: "These bands of gneiss altercating with the schist 

 are for the mosl part regular and bed-like in their characters, but their true 

 nature as iujected Bheets or dikes is sufficiently revealed." 



It will he tinted in the above table that the thickness of the schist beds 

 gradually diminishes from top to bottom, while that of the gneiss beds grad- 

 ually increases. This denotes advance from the gneissic side toward the 

 schistic. 



Whether these numerous and tenuous gneissic hands present the verisimili- 

 tude of " injected sheets or dikes" may be better decided after noting a 

 state of facts which has fallen under my own observation. On the north of 

 Guntlint lake a traverse was made northward from the Animikie slates to 

 the Saganaga gneissoid area. As usual a belt of crystalline schists was 



i si 2. — Relation 



crossed, though it did not exceed three hundred feel in breadth. This was 

 made ii | > of alternation- of rigidly parallel ami indefinitely extended bands 

 of uralitic schisl and a gneissoid rock. These became, in one pari of the 

 belt, so slender that I estimated thai five hundred alternations occurred 



within the -pare of fifty feet. This would give Inn an inch and tWO-tenths 



for the mean thickness of each. Bui many of them were thicker than this, 

 while many others wen- attenuated to a thickness of half or a quarter of an 

 inch. And \ei each preserved a rigid continuity of direction. 

 The structural relatione of the granitoid, gneissoid, and Bchistoid rocks 



i/ , pi 



