I 88 STRATIGRAPHICAL GEOLOGY. 



great antiquity is to be ascribed to the highly crystalline texture of many of their more 

 conspicuous rocky masses, which, until closely scrutinized, do certainly bear a near 

 resemblance to the typical forms of the most ancient gneiss, mica slate and granite. 

 But it involves we conceive two errors, first, that of assigning to all the strata of the 

 gneissoid class, merely in virtue of their crystalline aspect, a date remoter than that of 

 the protozoic or earliest fossiliferous deposits ; and secondly, the error of supposing 

 that the strata of these mountains contain no organic remains. So long as their fossil- 

 iferous character was undiscovered, the metamorphic condition of these rocks might 

 naturally enough deceive the observer, and lead him to false inferences in relation to 

 their age. 



Having in the month of July last, enjoyed the opportunity of studying with some care 

 the structure and composition of that part of the chain which is exposed to view in the 

 picturesque and deep defile of the Saco, we had the good fortune to detect in the vicin- 

 ity of the Notch, the fossiliferous character of a portion of the strata, and to see through 

 the metamorphic disguises in which intense igneous action has obscured these origi- 

 nally sedimentary palaeozoic masses. We succeeded in determining some of the organic 

 remains sufficiently to identify thereby some of the formations, much altered as they 

 are from the purely sedimentary aspect, and from these data we have attempted to 

 deduce some inferences respecting the //;//// of aittiqnity of these mountains, and the 

 date of their elevation. By detecting in many of the pseudo-granitic rocks a genuine 

 sedimentary stratification, we were able to follow in sundry places the true direction 

 of the almost obliterated bedding, and to discover the course of the anticlinal axes. 

 These once clearly recognized, led us finally to conclusions which have much interested 

 us in regard to the structure of the whole chain and the nature of the forces of eleva- 

 tion. In the present short paper we j^ropose to submit a concise abstract of these 

 observations, and the results to which they have brought us. 



By inspecting the accompanying little map, the reader will notice that the general 

 direction of the Gorge of the Saco, neglecting the local windings in its course, is 

 nearly from north to south. In one place, about half-way between Crawford's and the 

 Willey house, the contracted valley as we trace it south bends abruptly to the west- 

 ward, and in the distance of perhaps a furlong sweeps back again into its former south- 

 erly direction, making a double or sigmoid curve. This feature is especially favorable 

 to the exhibition of the range and dip of the rocks, which are here exposed endwise 

 in the transverse section. In the mountain on the north and west of the Gorge, the 

 end of which is full in front of the traveller as he ascends the valley from the Willey 

 house, the stratified structure of the rocks throughout this gigantic ridge, is plainly to 

 be seen in the differently colored perpendicular belts which outcrop edgewise along its 

 naked and nearly mural face. 



At the Notch (represented in the sketch at a) the rocks on both sides of the narrow 

 chasm are traversed by two sets of nearly vertical planes or joints, the one running 

 nearly N. E. and S. W., the other nearly N. W. and S. E. Though in this place the 

 stratification is but obscurely indicated, we succeeded in making out the planes of 



