94 AUSTRALASIAN ANTARCTIC EXPEDITION. 



If any theory can replace opposition by harmony such a theory will grow in strength 

 as each new concordance is produced from the field of geological literature. The 

 theories of metamorphic differentiation and metamorphic diffusion which appear to 

 account for certain features at Cape Denison seem to be applicable in other areas. In 

 some cases they produce interpretations quite different from the published explanations, 

 and the value of these interpretations depends partly on the assurance that can be 

 given to the Cape Denison phenomena and partly on the value that can be attached 

 to Grubenmann's great work, " Die Krystallinen Schiefer." In many cases it has seemed 

 to us that the description of the products of metamorphic diffuson and metamorphic 

 differentiation are better than those which have been presented from Cape Denison. 

 The Cape Denison descriptions have necessarily suffered from our inability to revisit 

 the area. The field work could not be revised with the progress of the work in the 

 laboratory, and the conclusions cannot be forced home with the wealth of evidence 

 that might otherwise have been available. 



We propose now to examine the data from some of the other areas from the stand- 

 point that the Cape Denison study has created. Attention is only given to a few 

 recent and important publications, and the criticism is offered to stimulate interest 

 and to direct attention to explanations which have not been hitherto considered. 



2. NORTH- WEST HIGHLANDS OF SCOTLAND. 



Features at Cape Denison and Cape Gray are reflected in the areas of Lewisian 

 gneiss in the North-West Highlands of Scotland. The Lewisian gneiss (p. 41)* has been 

 subdivided into 



1. Fundamental Complex. 



2. Ultra basic dykes. 



3. Basic dykes of dolerite, epidiorite (amphibolite), hornblende schist. 



4. A few dykes of exceptional composition. 



5. Granites and pegmatites. 



Groups 2 and 3 have been found to be associated with the Lewisian gneiss, and yet 

 intrusive into the Fundamental Complex, and are so referred to the pre-Torridonian. 

 Teall remarks (p. 39) that in many places the dyke-like character is obvious, as more 

 or less vertical walls of black rock clearly cut across the gneissic banding. But, in 

 other places, owing to movements after or during the injection of the dykes, the dyke- 

 like character is lost and the rocks of the dykes become more or less incorporated with 

 the earlier complex. 



Home remarks (p. 36), in connection with the basic intrusions, that it is of special 

 importance to note that in the southern tracts, where the dykes are represented by 



1 The pages quoted in connection with this area have reference to the following publication : " The Geological Structure 

 of the North-West Highlands of Scotland," B. N. Peach, J. Home, W. Gunn, C. T. dough, L. W. Hinxman, J. J. H. TealL 

 Memoirs Geol. Surv. Gt. Britain, 1907. 



