TYPICAL LAURENTIAN AREA OF CANADA. 335 



The whole Laurentian system, including the anorthosites, is 

 in many places cut by numerous dykes of large size, which can 

 often be traced for great distances. These are of several kinds, 

 the principal series consisting of a beautiful fresh diabase often 

 holding quartz in considerable amount in micro-pegmatitic inter- 

 growths with plagioclase. Other sets of dykes and eruptive 

 masses consisting of augite and mica syenites, quartz-porphyries 

 and other rocks are also known to occur but have not as yet 

 been carefully studied. 



The Hastmgs Series. — The stratigraphical relations of the 

 Hastings series have not as yet been satisfactorily determined. 

 The rocks constituting the series differ widely in petrographical 

 character from those of the Fundamental Gneiss and the Gren- 

 ville series, both of which are supposed to occur in its immediate 

 neighborhood. The series consists largely of calc-schists, mica- 

 schists, dolomites, slates and conglomerates, thus containing much 

 material of undoubtedly clastic origin. It has moreover a very 

 local development, being confined, so far as at present known, 

 to one small corner of the area, as has been mentioned. It was 

 by Logan supposed to come in above the Grenville series, while 

 Vennor v»'ho subsequently examined the district, believed it to 

 be equivalent to the lower part of this series. That we have in 

 the Hastings series a comparatively unaltered part of the Gren- 

 ville series, made up largely of rocks whose origin is easily rec- 

 ognized, would be a most important fact if established, and 

 would, of course, afford a key to the whole question of the 

 origin of the latter. This is a conclusion, however, which cannot 

 be accepted until supported by very clear and decisive evidence, 

 especially as the stratigraphy of the Hastings district is very 

 complicated, the several series represented in it being much 

 folded and penetrated by great masses of eruptive rocks. The 

 whole district has also been subject to great dynamic action, 

 some of the pebbles in the conglomerates of the Hastings series 

 being distorted in a most remarkable manner. This series may 

 prove to be merely an outlying area of Huronian rocks folded in 

 with the Laurentian, and until the district has been studied in 



