98 AUSTKALASIAN ANTARCTIC EXPEDITION. 



from ultra basic rocks to basic rocks. On Plate III. of this memoir there is an 

 illustration of garnetiferous muscovite biotite gneiss with lenticles of " pegmatite." It 

 can be pointed out that these lenticles may be fragments of broken pegmatite veins, 

 but they are quite possibly metamorphic differentiation products, as the same quartzo- 

 felspathic material is distributed right through the base of the gneiss. 



If, then, the phenomena of metamorphic diffusion and metamorphic differentiation 

 be upheld, and the rock types be traced back with their aid to the primary types, we 

 must surely arrive much nearer the true history of the Fundamental Complex in the 

 Highlands. If the Complex be studied from the view point of these theories it seems 

 possible that some of the apparent complexity will disappear. The rocks must no longer 

 be approached through the eyes of a mineralogical classification, as attempted by Teall, 

 which obscures relationships and separates similar rocks. True metamorphic types 

 must be recognised, and the kata zone, meso zone, and epi zone varieties of the same 

 type must be correlated together according to Grubenmann's method or to some 

 analogous system. Metamorphic diffusion types and metamorphic differentiation types 

 should also occupy divisions in the mental field of view before it would be possible to 

 present an orderly exposition. 



3. HALIBUBTON AND BANCROFT AREAS, CANADA. 



Amphibolites are recognised as forming an important part of the Canadian Archaean 

 rocks, and considerable study has been given to them by Adams and Barlow in the 

 Haliburton and Bancroft areas in the Province of Ontario. Their work is embodied in 

 a memoir published by the Geological Survey of Canada in 1910*. Papers containing 

 their results appeared earlier in the Quarterly Journal of the Geological Society of 

 Londonf and in the Journal of Geology^. In presenting criticism on that portion of 

 their work which pertains to amphibolites, attention is only given to the memoir, the 

 latest and most complete publication. 



From a study of this memoir we find that it appears to be claimed that amphibolites 

 are formed in diverse ways throughout the area. According to these different modes 

 of origin the amphibolites may be classified in the following manner : 



| 



1. Those derived by alteration of basic dykes or similar igneous intrusions 



(a) Those which can now be recognised as true dykes. 



(6) Those which appear as bands in crystalline dolomite, &c. 



2. Those derived by alteration of limestones by action of intrusive granitic magma 



(a) Those which appear in a linear manner along the contact of the limestone 



masses and the gneiss. 

 (6) Those which appear as inclusions in the grey gneiss. 



" Geology of the Haliburton and Bancroft Areas," F. D. Adams & A. E. Barlow, Geol. Surv. Can. Mem., No. 6. 

 t " The Laurentian System in Eastern Canada," F. D. Adams. Q.J.G.S. 1908, p. 127. 

 t " On the Origin of the Amphibolites of the Laurentian Area of Canada," Journ. Geol., 1909, vol. 17, p. 1. 



