596 THE JOURNAL OF GEOLOGY. 



of the lake, and of the gabbro, diabases, diorites, melaphyres 

 and porphyrites of the Keweenawan overlying the Penokee 

 series to the north, while Hall x has described a few hand speci- 

 mens of diabases and gabbros from the Archaean of Central Wis- 

 consin. 



Further, in a discussion as to the nature of the diabase sheets 

 interbedded with the Animikie slates and quartzites in Minne- 

 sota and Canada, which leads to the conclusion that the former 

 are subsequent intrusions between the clastic beds, Lawson 2 

 gives a short generalized description of the petrographical char- 

 acteristics of these rocks, and in a second article 3 he treats of 

 the structure and composition of the anorthite rock of Irving, to 

 which he gives the name anorthosyte. Finally, the writer in two 

 articles refers to the coarse gabbro 4 of north-eastern Minne- 

 sota and to the peridotites and pyroxenites 5 associated with it 

 along its northern border. 



W. S. Bayley. 



1 C. W. Hall : Notes of a Geological Excursion into Central Wisconsin. Bull. 

 Minn. Acad. Nat. Sciences, III., No. 2., p. 251. 



2 A. C. Lawson : The Laccolitic Sills of the Northwest Coast of Lake Superior. 

 Bull. No. 8, Geol. and Nat. Hist. Survey of Minnesota, p. 30. 



3 A. C. Lawson : The Anorthosytes of the Minnesota Coast of Lake Superior 

 lb., p. 2. 



4 W. S. Bayley : A Fibrous Intergrowth of Augite and Plagioclase, resembling a 

 Reaction-rim, in a Minnesota Gabbro. Amer. Jour. Science, XLIII. 1892, p. 515. 



5 W. S. Bayley : Notes on the Petrography and Geology of the Akeley Lake 

 Region, in North-eastern Minnesota, 1892, p. 193. 



