12 



TRANSACTIONS OF THE 



They do not exhibit themselves in situ in the nar- 

 rows at a higher elevation than about fifty feet above 

 the Juniata 7 and occupy merely a strip of the breadth 

 of one-sixth of a mile. At the western termination of 

 the Shade mountain we find this deposit not only ex- 

 panded over an area a mile in breadth at least, but at- 

 taining an elevation of three hundred and fifty feet ; 

 the whole mass descending, as we have before stated, at 

 a small angle towards the west. 



The Juniata cuts across the Fucus beds at this point, 

 traversing from the north to the south side of Shade 

 mountain ; and here this ridge having passed in a 

 straight line for more than forty miles from the Susque- 

 hanna and having maintained a uniform elevation 

 throughout, loses its bold character and terminates in a 

 gentle slope to the river. Through the comparatively 

 soft strata which contain the vegetable remains, the Ju- 

 niata has in the lapse of ages, effected a passage, first 

 transversely, and then longitudinally down the gorge, 

 and during this process a large portion of such strata 

 have evidently been removed. These details are illus- 

 trated by the map and section. PI. iv. fig. 6, and PI. iii. 

 fig. 7, by which it wiU be perceived that the stratifi- 

 cation of the two^ridges incline toward each other, at 

 an angle of about fifty degrees, and if prolonged would 

 meet beneath the centre of the trough ; and as the fu- 

 cus beds seem to rest upon both, as a filling up, it is 

 obvious why we incline to the opinion before given 

 that this deposition was effected at a period subsequent 

 to the upheaving of the ridges. 



