GNEISSIC FOLIATION. 115 



19. Beiblatter zu den Annalen cler Physik und Chemie, 1886, No. 1. 



20. Journal deg Societes Scientifiqiies, 27 Jan., 1886. 



21. (1) Notice sur I'ficole ceutrale des Arts et Manufactures, 1883, Paris. 



(2) Programme des Conditions pour I'Admission des Eleves. 



(3) Arrete Ministtiriel. 24 Mai, 1862. 



22. Atti della Societa Veneto-Trantina di Scienze Naturali residente in Pa- 



dova. Vol. IX., Fascicolo I., II. 



Total, 48. 



The following were elected members : H. Piper, Adolphus 

 Baxter, and Anthony McGill, B.A. 



The President, on behalf of Mr. A. C. Lawson of Ottawa, 

 read a paper entitled : " Some Instances of Gneissic Foliation 

 and Schistose Cleavage in Dykes and their bearing upon the 

 Problem of the origin of The Archaean Rocks." 



The phenomenon of gneissic foliation and schistose strncture in 

 rocks is so many-sided in its character, and so far reaching in its 

 bearing upon the ehicidation of important problems in ai'chean 

 geology, that a comprehension of these physical characters, suffi- 

 ciently adequate for the formulation of an acceptable theoiy explana- 

 tory of their origin and development, is one of the great desiderata 

 of the geological science of to-day. Such a comprehension can only be 

 arrived at after careful and intelligent sifting of evidence gathered by 

 much patient research in many fields. That we are as yet far from 

 having accumulated sufficient evidence upon which to base a reliable 

 and consistent hypothesis will be conceded by all geologists who 

 have gone, hammer and compass in hand, into the archean field and 

 faced the problems there presented. In the whole range of geology, 

 whether we regard it from a purely philosophic or a strictly eco- 

 nomic point of view, there is no more important general question to 

 be solved than that of the original chai-acter and present structui-e of 

 the archean system of rocks ; and for the solution of that question 

 one of the great reagents that is lacking, is, I believe, a good working 

 hypothesis, or, if necessai'y, two distinct hypotheses that will give us 

 the most highly probable explanation of these two phenomenal rock 

 structures, viz.: gneissic foliation and schistose cleavage. 



They are both so familiar and commonplace to all geologists that 

 objection may be made to classing them as phenomenal, but so long 

 as they are without a rationally consistent explanation they may fitly 



