10 



TRANSACTIONS OF THE 



grauwache group was formed under a quiescent state 

 of the antediluvian waters. The F. Alleghaniensis 

 has with propriety been classed with the most interest- 

 ing fossil productions of this continent. A single slab 

 in your cabinet, ornamented in relief with groups of 

 this remarkable fossil, whose figured surface reminds us 

 of the Gothic tracery of ancient sculpture, is of itself an 

 object of admiration. Imagine beds of these, miles in 

 extent, deposited or rather accumulating growth after 

 growth, and layer over layer, and you will have one 

 more subject for contemplation, in addition to the innu- 

 merable others, which result from our inquiries into 

 the u Remains of a former world. " 



Since the preceding passages were written, I have 

 again explored the position of the fucus beds in the 

 Shade mountain, and am enabled to subjoin a few addi- 

 tional notes. 



It may be premised that in estimating the position 

 and areas of the various deposits in this vicinity, no 

 small perplexity arises from their curvatures or contor- 

 tions. Erroneous impressions relative to their prevail- 

 ing inclination and direction, must not unfrequently re- 

 sult from the inspection of detached sections. It is only 

 by a continued series of observations, under propitious 

 circumstances at various points, and at different seasons 

 of the year, — for even the season of snow is favorable 

 to the exhibition of some of the broader geological fea- 

 tures in mountainous districts — that the intricacies of 

 such deposits can be unravelled. This remark is 

 strictly applicable to the entire valley of the Juniata, on 



