484 W. H. HOBBS — LINEAMENTS OF ATLANTIC BORDER REGION 



Introduction 

 historical 



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Since the time of Elie de Beaumont and the promulgation of his some- 

 what fantastic pentagonal theory of the arrangement of mountain chains, 

 the attention of geologists has been largely withdrawn from the orienta- 

 tion of earth features and focused on the areal distribution of geologic 

 formations and the construction of geologic sections. It must be ad- 

 mitted on all sides that to this transference of effort has been due the 

 great advance which geology has made in the period which has since 

 elapsed. The question may now be asked, however, whether the accu- 

 mulation of geologic data and the replacement of the crude maps of the 

 earlier period by the accurate modern topographic map do not warrant 

 a return, if not to the methods of de Beaumont, at least to a new and 

 entirely different study of the orientation of surface features. May not 

 too much attention be now directed to inference regarding the section, 

 which is not often available for inspection, and too little to the ground 

 plan of features which are everywhere open to study. The trend which 

 has been given to geological thought in Europe, in particular by the 

 Baron von Richtofen in Germany, by Commandant Barre and others in 

 France, and throughout the continent of Europe by the distinguished 

 Viennese geologist, Professor Suess, tend greatly to strengthen this con- 

 viction. The prominence which the theory of Green, regarding the 

 genesis of the broader features of the earth, has of late acquired will 

 further emphasize the importance of the directional element in topo- 

 graphic development. 



The investigation discussed in this paper is an inquiry into the orien- 

 tation of the dominating earth lineaments of the Atlantic Border region, 

 with a view to determine whether they betray any law of systematic 

 arrangement. The inquiry was suggested by the study of the south- 

 western New England area, and the evidence discovered there of a com- 

 plex fault mosaic, the limits of which can only be assumed to be far 

 beyond the boundaries of the province studied. Such an investigation 

 has not hitherto been made within the region, and the scope of the in- 

 quiry presents novel features. 



CHARACTERISTICS OF JOINTS AND FAULTS 



The data collected by geologists respecting joints and faults have until 

 recent years not been of a sufficiently definite character to allow of 

 scientific correlation throughout large areas, or, in fact, even in very 

 limited areas. Under the best present theory of the formation of block 

 faults, their isolated occurrence is as little to be expected as would be 



