522 Reviews — Geological Survey of Canada — 



crystalline limestone, quartzite, garnet-rock, intrusive syenite, and 

 apparently deep-seated granite, are described in detail. The gneisses 

 are divisible into (1) those of igneous origin (pp. 38, etc.) ; (2) those 

 of sedimentary origin (pp. 49, etc.) with limestones and quartzites ; 

 and (3) some gneisses of doubtful origin (pp. 67, etc.). 



II. — Of the Anorthosite groups, that of the Morin area is first 

 described (pp. 85, etc.), as to its stratigraphy and petrology. It 

 varies in its constituents and structure, the latter frequently showing 

 the results of pressure and movement. At page 115 we read : — 



" It would thus seem that the clastic structure described as occur- 

 ring in these anorthosites occupies, in a way, a position intermediate 

 between the ' protoclastic structure ' of Brogger and the cataclastic 

 structure commonly observed in sheared rocks. 



"In the Morin area, then, we have a great intrusive mass of 

 anorthosite, or gabbro very rich in plagioclase, breaking through the 

 Laurentian, cutting off successive horizons, including portions of the 

 gneiss, sending an apophysis into it, and in some places bounded 

 by a zone of rock which exhibits many characteristics of a contact- 

 product. This mass in most places shows irregularities in size of 

 grain, and in some places a streaked or irregularly banded structure, 

 while in one part of the above-mentioned apophysis it is well foliated, 

 which foliated structure there is reason to believe is a secondary one. 

 It certainly does not represent a partially obliterated bedding, as the 

 earlier observers seem to have believed, while the other supposed 

 evidences of the existence of a great overlying sedimentary series, 

 of which it was supposed to form part, are also wanting ; the gneiss 

 and limestone with which it was thouglit to be interstratified really 

 belonging to the Grenville Series, while the apparent interstratifi- 

 cation of the anorthosite is due to intrusion. 



" The whole is furthermore unconformably overlain b}"- flat 

 unaltered strata of Potsdam and Calciferous age, and thus possessed 

 in Cambrian times the characters which it now presents ; while the 

 nature of the anorthosite, and its relation to the Laurentian, lead us 

 to suppose that it is much nearer in age to the latter than to the 

 overlying Cambro-Silurian, probably not miich more recent than the 

 Grenville Series itself." 



Other anorthosite masses, in seven distinct areas, are then 

 described (pp. 116, etc.), accompanied by a table of analyses of 

 various plagioclasic or anorthositic rocks, together with notes of the 

 occurrence of such rocks in Norway, Russia, Egypt, and the United 

 States. Post-Arch^an dykes are described at pp. 134, etc. This 

 Report also comprises valuable notes (pp. 139, etc.) on the economic 

 materials of the region, including iron-ores, graphite, apatite, mica, 

 " infusorial " (!) — probably diatomaceous — earth (used locally for 

 whitewashing buildings), garnet-rock,^ limestone, marble, and 

 anorthosite (some used for paving-stone). 



Report L, by A. P. Low (387 pages, including seven appendices, 

 with four plates and four maps), is on explorations in the Labrador 



' The hybrid and therefore very improper word " garnetiferous " is used throughout 

 this Report, wherever " garnet -bearing " could and should have been used. 



