Analytical Abstracts of Current 

 Literature. 



Summary of Current Pre -Cambrian North American 

 Literature. 



Prefatory Note. — The summary of current pre -Cambrian literature 

 beginning in this number, which will continue in following numbers, though 

 probably not consecutively, is made upon somewhat different principles from 

 those ordinarily used. The fundamental ideas of the plan are as follows : 

 The summary proper and the comments are kept wholly separate, in this way 

 preventing the confusion which frequently comes from a mingling of the two. 

 In the summaries the original language of the author is used as far as practi- 

 cable, although a single sentence may be taken from several sentences of the 

 original. Where it is disadvantageous to use the original language other 

 words are used. This often is necessary, because the language which is 

 adapted to complete exposition is often not the best adapted to lesume. No 

 quotations are made ; for the ideas contained, whether in the original 

 language or not, are wholly the ideas of the author, the whole is in fact 

 really quoted. It might be thought that better results would be reached by 

 indicating through quotations what words are taken from the original, but 

 this method would necessitate an unpleasant and constant alternation from 

 quoted to non- quoted phrases. As a result of experience with the two 

 methods, the editor feels certain that he is able more accurately and fully, in 

 a brief space, to represent the ideas of the original author by the method 

 proposed, than by following the usual method. 



The summaries are confined to articles or parts of articles pertaining to 

 pre -Cambrian stratigraphy. Purely economic or petrological articles are not 

 summarized unless they concern pre -Cambrian stratigraphy, in which case 

 the substance of the conclusions are given, rather than a full account of the 

 observations and the manner of reaching them. The abstracts have the 

 defects of all summaries, — a certain amount of inaccuracy, because many 

 modifying and qualifying facts can not be given, and because undue emphasis 

 is placed upon the conclusions. 



In many cases no comments are made. This does not imply that the 

 editor agrees with the statements of the summaries. To criticize, qualify, or 

 refute the statements of the authors in all cases of disagreement, would often 



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