Section of the Alleghany Mountain, ^^c. 435 



tion of those vast disturbed masses, which constitute the singularly 

 uniform ridges, and long straight valleys of central Pennsylvania, 

 east of the Alleghanies ; a subject on which the attention of a 

 geologist would be fitly employed ; which heretofore has re- 

 mained unnoticed, and which involves some extremely inter- 

 esting and extensive examples of displacement. 



The progress of such an investigation is as slow as laborious, 

 and the geologist contends with many natural difficulties. These 

 will ever be found in a country like that under consideration, 

 where the surface is obscured with a dense forest vegetation ; 

 where the operations of man have scarcely commenced ; where 

 neither artificial excavations, nor natural sections, nor exposed 

 escarpments, relieve the monotony of the mountain side, or the 

 gloomy ravine ; and where those elevated valleys, ramifying 

 amidst the intricacies of the mountain chains, have continued 

 from remote ages, and in all probability, for ages will remain, 

 an impenetrable wilderness, and an impracticable labyrinth. 



On account, therefore, of these impediments to ordinary and 

 individual examination, it is especially desirable, that geological 

 observations, made under the advantageous circumstances at- 

 tending public surveys, by engineers, and what is still better, of 

 the completion of the works committed to their charge, and con- 

 ducted at their leisure, should be faithfully recorded. This can 

 be advantageously effected by communications with Geological 

 Societies in the separate states, like that now coming into exis- 

 tence in Pennsylvania : but better still, upon the principle sug- 

 gested at page 130 of your Journal, if conducted under the 

 auspices of the government, as a branch of duty strictly in con- 

 nexion with the engineer department. In this respect, your 

 remarks are well deserving attention from the parties to whom 

 they have reference ; from those whose professional operations 

 place them in situations so particularly favourable to scientific 

 research, and more especially from the department whose pro- 

 vince it is to direct their movements. 



Reverting to our section, from which I have wandered, it 

 will be obvious, that on approaching the summit of the Alle- 

 ghany ridge, after intersecting the lower series to which 1 

 have referred, and estimated at upwards of 1300 feet in 

 thickness, we arrive at a conglomerate rock or pudding-stone, 

 composed of white quartz pebbles, set in a coarse grit. This bed 



