THE 



CANADIAN NATURALIST 



AND 



^uavtcrly f oiivnal of ^mim. 



THE HISTORY OF SOME PRE-CAMBRIAN ROCKS 

 IN AMERICA AND EUROPE. 



By T. Sterry Hunt, LL.D.,F.R.S. 



(Read before the American Association for the Advancement of Science, 

 at Saratoga, September 1, 1879.) 



I. Introduction. 



One of the earliest distinctions in modern geology was that 

 between the crystalline or so-called Primary strata, and those 

 which are found in many cases to have been deposited upon 

 them, and being in part made up of sediments derived from the 

 disintegration of these, were designated Transition and Secondary 

 rocks. While the past forty years have seen great progress in 

 our knowledge of these younger rocks, and while their strati- 

 graphy, the conditions of their deposition, and their geographical 

 distribution and variations have been carefully investigated, the 

 study of the older rocks has been comparatively neglected. This 

 has been due in part to the inherent difficulties of the subject, 

 arising from the general absence of organic remains, and from 

 the highly disturbed condition of the older strata, but in a greater 

 measure, perhaps, to certain theoretical views respecting the 

 stratified crystalline rocks. In fact, the unlike teachings of two 

 different and opposed schools lead to the common conclusion that 

 the geognostical study of these rocks is unprofitable. 



The first of these schools maintains that the rocks in question 

 are, in great part at least, not subordinated to the same structural 

 laws as the uncrystalline formations, but are portions of the 

 oriizinal crust of the earth, and that their architecture is due not 

 to aqueous deposition and subsequent mechanical movements, 

 Vol. IX. R No. 5. 



