302 Canadian Record of Science. 



true in an anorthosite of Essex county, New York, and 

 Sachsse 1 in a " Flaser-gabbro " from Eosswein, in Saxony, 

 but tbe material analysed in these two cases was not 

 quite pure. 



The gneiss which immediately surrounds the area has 

 a uniform character, and contains no crystalline limestone 

 as in the Morin area. It has, in fact, an older appear- 

 ance, and Logan would probably have classed it with the 

 the lower or fundamental gneiss of the Ottawa division. 

 This gneiss has, irrespective of local deviations, a strike of 

 K 20° to 60° E. Along the southern limit of the area it 

 strikes directly towards the anorthosite and is cut through 

 or overlaid by the latter. The line of contact of the 

 anorthosite with the gneiss forms a series of large curves* 

 which are interrupted at times by straight lines. The latter 

 most probably indicate faults. On the east and west sides 

 of the area the line of contact crosses several times the 

 Little Peribonka and the Shipshaw respectively, so that it 

 repeatedly cuts the direction of the strike of the gneiss. 

 What deserves notice is the fact that when the anortho- 

 site (which is mostly massive and has for that reason no 

 strike) shows any indication of streaked or foliated struc- 

 ture (and examples of this structure are clearly exhibited 

 on the east side of the area where the granular anortho- 

 site is principally found with broken fragments of plagio- 

 clase) this is identical in direction with the strike of the 

 gneiss, and is not affected by the intersecting line of 

 contact. This is no longer true, however, in the central 

 portion of the area, through which the Peribonka flows, 

 in the northern portion of its course, often between cliffs 

 1,000 feet high. Wherever the anorthosite exhibits a 

 strike in this part of the area, a thing which only excep- 

 tionally occurs, this differs from that of the gneiss as well 

 as from that of the anorthosite on either side, being N". 



i R. Sachsse, Uber den Feldspathgemengtheil des Flasergabbros von Rosswein.— 

 Ber. d. naturf., Ges. in Leipzig, 1883. 



