KNOWLEDGE OF EARTH STRUCTURE 157 



of the country. In this case, the disturbing force must have 

 acted beneath the primary rocks. And besides, we have good 

 evidence which will be shown by and by, that our new red 

 sandstone was formed beneath the ocean. We cannot then 

 reason on this subject from present levels." 



In 1840, H. D. Rogers, a geologist who has acquired a 

 more widely known name than Hitchcock, but who in 

 reality showed an inferior ability in interpretation, made 

 the following statements in explanation of the regional 

 monoclinal dip of the New Jersey Triassic rocks averag- 

 ing 15 to 20 degrees to the northwest : l 



"Their materials give evidence of having been swept into this 

 estuary, or great ancient river, from the south and southeast, 

 by a current producing an almost universal dip of the beds 

 towards the northwest, a feature clearly not caused by any 

 uplifting agency, but assumed originally at the time of their 

 deposition, in consequence of the setting of the current from the 

 opposite or southeastern shore." 



In 1842, at the third annual meeting of the Association 

 of American Geologists both H. D. and W. B. Rogers 

 argued (43, 170, 1842) against Sir Charles Lyell and E. 

 Hitchcock that the present dip of the Triassic was the 

 original slope of deposition, stating among other reasons 

 that the footprints impressed upon the sediments often 

 showed a slipping and a pushing of the soft clay in the 

 direction of the downhill slope. In 1858 H. D. Rogers 

 still held to the same views of original dip, 2 notwithstand- 

 ing that a moderate amount of observation on the mud- 

 cracked and rain-pitted layers would have supplied the 

 proof that such must have dried as horizontal surfaces. 

 The idea of inclined deposition is not yet wholly dead as 

 it has been suggested more than once within the present 

 generation as a means of escaping from the necessity of 

 accepting the very great thicknesses of this and similar 

 formations. Thus, as Brogger has remarked in another 

 connection, the ghosts of the old time stand ever ready 

 to reappear. 



In the present essay on the rise of structural geology 

 as reflected through a century of publication in the 

 Journal, attention will be given especially to two fields, 

 that of structures connected with igneous rocks and that 



10 



