64 JOURNAL OF GEOLOGY— SUPPLEMENT 



(canadites) and umptekites of Almunge, Sweden, are transitional 

 both into alkaline granites and nordmarkites and also into normal 

 sub-alkaline granites/ In the Bushveldt laccoHthic complex, the 

 succession, ultra-basic types, norites, granites, nephelite syenites 

 is developed and Brouwer emphasizes a significant feature in this 

 connection when he refers to the formation of "eenerzijds zeer 

 kwartsrijke, anderzijds veldspatoidvoerende gesteenten" by "dir- 

 recte differentiatie." As a third example, it may be pointed out that 

 Daly has himself detailed the evidences of a "genetic bond" 

 between the Kruger nephelite syenites, malignites, etc., and the 

 Similkameen granite/ 



Normally, the nephelite syenites and their relatives appear, then, 

 to fall naturally into a differentiation sequence, being intimately 

 related to quartzose t)rpes, as the field evidence indicates and as 

 chemistry would lead one to expect. It may, nevertheless, be 

 reasonably considered probable that some nephelite rocks, espe- 

 cially melilite-nephelite t3ipes, may be formed by the method 

 suggested by Daly. 



Harker^ has advanced the idea that the alkaline rocks owe their 

 origin to a certain type of earth movement distinct from that 

 brought into play during the formation of sub-alkaline types. 

 Harker admits that the connection is not understood, but seeks to 

 show that the distribution of the two branches is related to the 

 great tectonic features of the earth. So many exceptions have 

 been pointed out by Cross, Daly, and others to his general sub- 

 division, with Becke, into Atlantic and Pacific provinces, that its 

 validity will not be discussed further here. There remain, however, 

 certain tendencies in that direction, among them the striking fact 

 that the Rocky Mountain front in the United States lies approxi- 

 mately along a boundary between regions of dominantly alkaline 

 and dominantly sub-alkaHne rocks."* Harker has discussed this 

 feature in some detail for the state of Montana. The general con- 



^ P. D. Quensel, "The Alkaline Rocks of Almunge," Bull. Geol. Inst. Upsala, XII, 

 157. 



^ Geol. Survey Canada, Mem. 38, Part I (1912), p. 459. 



3 The Natural History of Igneous Rocks, p. 93. 



■• Daly, however, describes nephelite syenite, etc., from the heart of the Cordillera 

 {Geol. Survey Canada, Mem. 38, p. 488). 



