482 A. C. Lane — Divisions of the Fre-Camhrian. 



of word usage not requiring local knowledge, but rather matters of 

 English style, upon which one may rightly appeal to an English 

 audience for a fair and intelligent judgment, in regard to which the 

 writer differs from Van Hise. 



In the first place, while Van Hise no longer absolutely restricts the 

 Archaean to non-klastics, he does restrict it to pi'e-Huronian.' But, 

 as he clearly states, the term Archaean was introduced by Dana to 

 avoid the implication as to life of the term Azoic (and Eozoic) for 

 all the pre-Cambrian rocks, and was divided by Dana into two groups, 

 the Huronian and Laurentian. The excuse of Van Hise for thus 

 modifying the definition and denotation of the term and its connotation 

 is that to include "both pre-Cambrian groups under one name would 

 result in making two groups of rock to appear to be alike when, as 

 a matter of fact, they are radically different" — the same objection 

 that some feel against using the term Algonkian to include Keweenawan 

 and Huronian. 



"While he thinks that in so doing he carries out the " essential 

 intent " of Dana, the writer cannot agree with him. Nor did Dana 

 himself. In view of the fact that Van Hise has to use the synonym 

 pre-Cambrian fifty-three times in twenty-six pages, there would 

 appear some justification for those geologists who prefer to employ 

 the term in the original sense. It is not so bad if one does not 

 mind capitals in the midst of a word to write pre-Cambrian, but if one 

 needs to refer to time since, it is certainly clumsier to say post-pre- 

 Cambrian than post-Archaean. - 



But are they really so "radically different"? Van Hise has shifted 

 his definition. It is no longer the distinction between klastic or not. 

 He makes it very clear that it is not 'zoic,' and a lack of clarity 

 exists, which, as it is absent from the style of this clear and 

 forceful writer, seems rather imaginary. An extra widespread and 

 important unconformity between them, a greater proportion of normal 

 sediments in the later division or Huronian, and very great difficulty 

 in applying ordinary stratigraphic methods to the earlier pre-Cambrian 

 — these appear to be the bases of division. But it is clear, it is indeed 

 emphasized by Van Hise, that division on such lines is essentially 

 local, unless one could show some reason why all over the earth at 

 the same time there should be a great unconformity, as when the 

 moon went off. 



It would seem to the writer on such (jrounds impossible to be sure, 

 for instance, that the Kona Dolomite of the lowest Huronian might 

 not be the equivalent of the Grenville Limestone of the Up2)er 

 Laurentian. 



It is unfortunate that in a paper devoted to discussing the division 

 of the pre-Cambrian, by an oversight Van Hise should forget to 

 mention the early thesis of the eminent geologist Credner on this 

 subject,' while he pays so cordial a tribute to Pumpelly and Marvine, 



> If we remove the Keweenawan to the Cambrian, the Algonkian becomes a sjTionym, 

 around Lake Superior at least, for Huronian. 



- Cf. Becker in the same Bull. Geol. Soc. Amer., 19, p. 128. 



3 " Die Gliederung der eozoischen (vorsilurischen) Formationsgruppe Nord 

 Amerikas": Zeitsch. fiir die Ges. Wiss. , 1868, xxxii, pp. 353-405. 



