OF THE APPALACHIAN CHAIN. 481 



Tiamical actions which the region has experienced, to the strata- 

 graphical arrangement of the rocks, and, as immediately connected 

 with this, to the distribution of thek organic remains. The object 

 of the present paper is, to exhibit those general laws of structure, 

 of which the feature in question is but a simple and immediate 

 consequence, and to develope what we have for several years past 

 regarded as the true theory of the flexure and elevation of the 

 Appalachian rocks. 



History of the previous Explanations of the general south- 

 easterly Dip in the Great Appalachian Valley. 



The first published attempt at explaining the seeming anomaly 

 of a general southeasterly dip across the great valley, was made 

 by Prof. Hitchcock, in the first edition of his Report of the Geol- 

 ogy of Massachusetts, in 1833. This explanation, which was 

 confined to the phenomena of western Massachusetts, supposes 

 a series of unconformable deposits all dipping to the east, at dif- 

 ferent angles ; but Prof. Hitchcock does not suggest the idea of 

 either an inversion or a folding of the rocks. 



At an early period in the geological surveys of New Jersey, 

 Pennsylvania, and Virginia, we were struck with the gi-eat prev- 

 alence of the soLitheasterly dip of the strata throughout the portions 

 of the Appalachian chain traversing those States, and recognized 

 its dependence on the oblique or inverted folding of the strata. 

 This will appear from the descriptions we have given of the phe- 

 nomena, in our Annual Reports for 1837 to 1839. The important 

 general law of a greater steepness of the dip on the northwestern 

 than the southeastern sides of the anticlinal axes, became known 

 to us at the same stage of our inquiries, and was first announced 

 in the Final Report on the Geology of New Jersey, \\Titten in 

 1839, and published early in the spring of 1840. 



Our solution of this question of the southeasterly dips, which 

 we have long supposed to constitute the only key to the structure 

 of our great mountain chain, was communicated in conversation 

 to Professors Hitchcock and Emmons, at the first Annual Meet- 

 ing of the Association of American Geologists, in the spring 

 of 1840. 



