I 916 ] Lawson: Correlation of Pre-Cambrian Rocks 



3 



problem. "Workers in particular closely grouped fields may ignore the 

 work going on in other fields and publish their observations as if the 

 latter did not exist, and so, perhaps, promote the intensity of their own 

 activity ; but this attitude after all is only an expression of the prin- 

 ciple of subdivision of labor, and implies that others must do the 

 equally important work of collation, comparison and generalization. 

 Every competent attempt at generalization from a reasonable amount 

 of data is a step in advance in so far as it corrects the errors of earlier 

 efforts. The discarded generalizations, the succession of which creates 

 so much disgust in the minds of some, are merely hypotheses which 

 have served their purpose and have been supplanted by others which, 

 in most cases, are nearer the truth. The normal procedure in scien- 

 tific progress is the modification of hypotheses, and the discarding of 

 generalizations as expressed in correlation tables, etc., is only an ex- 

 emplification of this procedure. The odium which attaches to errone- 

 ous correlation tables fades away when we regard them in their true 

 light as hypotheses put forward to stimulate inquiry as to their 

 validity. 



These hypotheses are the more necessary and the more useful in 

 geology because of the vastness of the field of observation, the expense 

 attaching to the work, and in pre-Cambrian geology, because of an 

 international boundary which precludes survey officers of one country 

 from fully familiarizing themselves with the field relations in the other. 

 These conditions make it impossible for the individual geologist thor- 

 oughly to test a hypothesis that may explain his own particular field, 

 and he is under the necessity of publishing it in order to secure co- 

 operative criticism from other fields. In most other sciences the indi- 

 vidual worker may more conveniently put his hypothesis to the test 

 before publication, and there are in these sciences doubtless as many 

 discarded hypotheses as in geology, though perhaps not so many have 

 been published. 



Having thus persuaded myself that tentative generalizations are a 

 useful if not a necessary part of the method of advancing our knowl- 

 edge of pre-Cambrian geology, I shall proceed to review briefly some 

 phases of our present knowledge of this field and to formulate still 

 another correlation table. I am moved the more to do this because of 

 the recent publication of a correlation table by Allen and Barrett, 2 to 

 certain parts of which I dissent on the ground that it does not take 

 sufficient cognizance of the relationships established in other fields. 



2 Jouru. Geol., vol. 23, no. 8, p. 689, 1915. 



