EfiSUMfi OF LITERATURE. 91 



The Laurentian gneiss is represented in the Vermihon district by the 

 Basswood Lake and perhaps the Saganaga Lake granite. However: 



There maj^ be spots, or considerable areas, within this original gneissic belt, 

 where, by subsequent deep-seated hydrothermal fusion, these primitive Laui'entian 

 sediments have been rendered plastic and then fluid, and have by pressure been 

 extended through fissures in the crust to the surface or have been uncovered as lacco- 

 lites by the destruction of the overlying strata; but wherever these exist they are 

 presumed to show their later origin by their nongneissic structure, or by their 

 overlying some later sedimentary^ strata. The distinction, however, between the 

 eruptive condition of the fused Laurentian sediments and the primitive sediments 

 that have been converted in situ into the fundamental gneiss is one that requires 

 more study before it can be defined. That both conditions exist there can be no 

 question; that they can always be distinguished is not to be affirmed [p. 29]. 



Closely associated with the belts of fundamental gneiss are areas of 

 massive erruptive syenite which have resulted from such hydrothermal 

 fusion of the gneiss. Such syenite is found north of Gunflint Lake, on the 

 shores of Cacaquabic Lake. 



The Laurentian gneisses are seen at places to be conformable with, 

 and to gTade into the hornblendic and micaceous "crystalline schists" — the 

 Vermilion schists, which are the equivalents of Lawson's Coutchiching. At 

 other places the gneisses and schists are uncomformable and here they both 

 play the role of eruptive rocks interpenetrating, in the form of transverse 

 dikes, and inclosing fragments of each other. This relationship is con- 

 sidered to be evidence of volcanic action. "It is manifest, therefore, that 

 the supposition of the advent of a characteristically eruptive era, closing 

 the quiet Laurentian sedimentary age, will account for both an unconform- 

 able and a conformable transition, such as are seen, from the Laurentian to 

 the Vermilion" (p. 35). 



The Vermilion group jjasses by conformable transition into the Keewa- 

 tin. The character of the Keewatin rocks indicates that there was active 

 volcanic action during the whole period, and that the ejectamenta were 

 received and distributed by the waters of the sm'rounding sea. This is 

 indicated by the alternation of the breccias and volcanic material with 

 truly sedimentary strata. The name Kawishiwin is proposed for the 

 massive greenstone stage of the Keewatin. The Keewatin is the iron- 

 bearing formation. The iron ore is associated with the jaspilite, which 

 is of a sedimentary origin. Above the Keewatin is a profound uncon- 



