606 Br. T. Sterry Sunt — Tlie Eozoic Rocks of N. America. 



is found in France, Austria, and Greece, while the preceding Ameri- 

 can floras are not. This kind of speculation, however, is very 

 fascinating, and would carry us far bej'ond the object in view, 

 namely, to contribute towards the determination of the relative ages 

 of the British and American Cretaceo-Eocene series. 



If the considerations I have brought forward were allowed to 

 prevail, the entire Cretaceous series of America would have to be 

 classified as Eocene, or at least placed considerably above the 

 Maestricht limestone. Most of the greatest geologists of America, 

 together with such distinguished Europeans as Lyell, D'Orbigny and 

 Pictet, have concurred to correlate them with oui's from the Ganlt 

 to the "White Chalk. The divei'gence of opinion concerning them, 

 and its discussion, has been almost limited to whether one of the 

 latest stages, the Laramie (which my views would make Middle 

 Eocene) is Cretaceous, post-Cretaceous, or Eocene. The vast 

 geological and biological importance of the question I have now 

 raised is therefore apparent. I am not presumptuous enough to 

 set an individual opinion in opposition to that of the great leaders 

 of science, nor vain to suppose that it would carry any weight; 

 but the chance that has led me to collect our British Eocene plants, 

 has also enabled me to make observations from them that have been 

 shared by few : and my hope in recording these now is, that they 

 may receive such attention as they may deserve, if those we justly 

 look upon as our teachers should think it worth while to reinves- 

 tigate the subject. 



V. — The Eozoic Eocks of North America. 

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



THE following is an abstract of Dr. Hunt's paper. According to 

 the author there is found among the pre-Cambrian strata of 

 North America an invariable succession of crystalline stratified 

 rocks, which have been by him divided into several great groups, 

 the constituents of which become progressively less massive and 

 less crystalline until we reach the sediments of Palaeozoic time; of 

 which the Cambrian is regarded as the basal member. Since all of 

 these pre-Cambrian rocks, with the exception, perhaps, of the lowest 

 or fundamental gneiss, present evidences, direct or indirect, of the 

 existence of organic life at the time of their deposition, it seems 

 proper to include them under the general title of Eozoic, proposed by 

 Sir J. W. Dawson. That of Archaean, employed by some geologists 

 to designate these pre-Cambrian rocks, appears too indefinite in its 

 signification, and, moreover, is not in accordance with the nomen- 

 clature generally adopted for the great divisions succeeding. These 

 Eozoic rocks include both the Primitive and the Transition divisions 

 of Werner. 



We. distinguish at the base of the Eozoic series a massive and 

 essentially granitoid gneiss. To this fundamental rock, sometimes 

 called the Ottawa gneiss, and of unknown thickness, succeeds what 

 has been named in Canada the Grenville gneissic series, made up in 

 great part of a gneiss somewhat similar to that last mentioned, with 



