31 6 ROLLIN T. CHAM BERLIN 



cause of extensive changes in sedimentation; and these, together 

 with chmatic and other effects that follow, influence profoundly the 

 life-development. Thus, back of both stratigraphy and paleon- 

 tology lies diastrophism, which furnishes the conditions upon which 

 they depend.^ If periods of diastrophism are thus truly the ulti- 

 mate basis of correlation, they form a subject of inquiry of prime 

 importance. 



The chief purpose of the study upon which this paper is based 

 is to determine to what extent past diastrophic movements of the 

 higher order actually have taken place — simultaneously in different 

 parts of the globe and periodically in the same region — with a view 

 to the bearing of the facts on the determination of systems and 

 periods, and on the broader correlations of geologic events. It is 

 an attempt to test the hypothesis that the geologic periods repre- 

 sent, in the main, periods of relative quiescence, during which there 

 were sea-transgressions and widespread sedimentation, and that 

 they were separated one from another by diastrophic disturbances 

 of shorter duration. The study is an attempt to discover whether 

 the principal manifestations of diastrophic activity in one portion 

 of the globe can be correlated approximately with corresponding 

 disturbances in other parts of the globe, and whether the synchro- 

 nous disturbances have been sufficiently widespread and effective 

 in their manifestations to constitute a satisfactory basis for dividing 

 geologic time into periods. 



There can be little doubt that there are various grades of defor- 

 mation and that most or all of these are serviceable as markers of 

 time divisions of some order, but in the present discussion I shall 

 try to limit the deformations recognized to those that involve some 

 notable folding, or at least to unconformities so marked as to imply 

 notable warping somewhere. This paper will be further limited 

 in that it offers merely a preHminary selection of data relative to 

 earth movements of the Paleozoic era that have been gathered from 

 various accessible sources but not yet fully traced to their original 

 sources and critically examined. The data are a part of a more 

 general collection which includes the Mesozoic and Cenozoic eras. 

 The present paper is but a modification of one read at the Twelfth 



'^ T. C. Chamberlin, "Diastrophism as the Ultimate Basis of Correlation," Jour. 

 Geol., XVII (1909), 692. 



