W. G. Foye — JYephelite Syenites of Ontario. 433 



(4) A liberal estimate of the nephelite syenite bodies mapped 

 in the Haliburton region would place their total area below 

 sixty square miles, or less than ten per cent of the area of the 

 amphibolites. 



(5) The amphibolites derived from impure lenses in the 

 limestone and those derived from gabbro by dynamic meta- 

 morphism are insignificant in amount when compared with 

 the amphibolites derived from the limestone by contact meta- 

 morphism. 



In view of these facts, it is desirable to know whether the 

 solutions which transformed the limestones to amphibolites 

 were segregated from the granite by juvenile gases, as Smyth 

 has suggested, or whether the interaction of the limestone and 

 the granite caused these solutions to be given off during the 

 formation of the amphibolites. 



It is clear from the following analyses that the amphibolites 

 did not result from a simple reaction between definite propor- 

 tions of the granite magma and limestone. Soda, potash, alu- 

 mina, and silica are present in the amphibolites in proportions 

 very different from those in the granite. 



Table III. 



Analysis of Analysis of 



Typical Bed Amphibolite 



Gneiss 



Si0 2 76-99 per cent 50-00 per cent 



TiO, 0-82 



A1 2 3 12-45 18-84 



Fe,0, 1-03 2-57 



FeO 0-49 5-51 



MgO 0-21 4-63 



MnO tr. tr. 



OaO 0-98 10-65 



Na,0 3-46 4-46 



K 2 4-29 1-18 



H,0 0-26 1-00 



CI none 0-10 



S 0-03 



CO none 0-10 



100-16 



99-97 



Before discussing this matter, the writer wishes to state a 

 theory concerning the method of emplacement of the Lauren- 

 tian granite and the origin of lit-par-lit structure in the Hali- 

 burton area. It is his purpose to treat the subject in more 

 detail at a later time. 



The Grenville series is very thick ; how thick, no one wishes 

 to state. Granite pegmatite penetrates this series in every 



