156 REPORT OF THE AMERICAN COMMITTEE. 
be the same, and all that varied would be the guess as to the 
importance of the time it represented. No geologist will contend 
that we have the data for settling such questions at the present 
time. As pointed out by Prof. Dana, the strongest break in the 
whole Paleozoic column is between the Lower and Ujiper Silurian ; 
no fact therefore like that just alluded to need stand in the way 
of the provisional classification of the entire Pre-Cambrian 
rocks as Archean (voted by the Congress), with two principal 
divisions.* 
Neglecting the unessential elements, such as names, there seems 
to be a fair agreement among working geologists in favor of giv- 
ing a name to the Pre-Cambrian ; of considering it at present as 
consisting of at least two parts ; of preserving the v/ord Lau- 
rentian for its lowest member, and of adopting a word as non-com- 
mittal as possible for the other. 
This preference also seems to be shared by many foreign geol- 
ogists. Thus the French propose to call the Pre-Cambrian rocks 
" Primitive," and to divide them into (1) Fundamental Granitoid 
Gneiss, and (2) Schistose Gneiss and Mica Schists ; Amphibolic 
Gneiss; (3)Cipolin ; Chlorito-Sehists. The Portuguese projwsed to 
call the lowest division of rocks " Primitive " or " Azoic," which 
should consist of one system, " Crystallophyllic;" which latter 
should have but one Series, or Laurentian. Above this the 
* Archeic 'f System with the Huronian Series is at the base of the 
Paleozoic. The Roumanian Committee arranges them " Group 
— Primitive; System — Archeic; Series — Etage, Huronian and 
Laurentian." To all intents these plans agree with that above 
which, it was thought, might harmonize the views of American 
geologists. 
B}' the manner of putting the two questions relating to the 
Pre-Cambrian rocks at Mr. Firket's suggestion, viz. : " 1st. Shall 
they be called Archean or Primitive? 2d. Shall they constitute a 
Group or System?" not so much the relative value of these terms, 
Group or System, as the decision by the Congress whether the Pre- 
* See Note 1, p. 184. 
t It is appropriate here to call attention to a singular inconsistency in spell- 
ing the word 'Archean.' Surely, if the adjectives Kaivo; and UaXaio; make 
Cen- and Pale-, Apxatog ought to produce Arche-. Prof. Dana in replying to a 
letter addressed to him on this subject acknowleges the justice of the criticism 
but says that he adopted the other spelling to avoid misapprehension. 
