of North America. S^l 



and at 500 ft. above the Juniata ; and specimens have even 

 been obtained from the summit. 



The strata I have enumerated dip towards the north-west 

 generally ; but local derangements have occasioned some par- 

 tial curvatures and arching of the inferior strata, so as to 

 occasion a variation from 30° N.W. to 60° S. The valley of 

 the Juniata is remarkable for the singular contortions, on a 

 large scale, of the strata upon its banks. 



Lower down the Narrows succeeds a variety of argillaceous 

 beds, which furnish the flagstones for the side pavements of 

 the town of Lewistown. The surfaces of these pavements 

 are covered with irregular protuberances, evidently of vege- 

 table origin, and, probably, another species of fossil ^'Igae, 

 Beyond this point another series of strata occurs. These 

 consist of red sandstones, interlaced with numerous veins of 

 white quartz, and conglomerates of granulated quartz, inter- 

 mixed with fragments of red micaceous slate. Even these 

 rocks occasionally exhibit coarse impressions and casts of 

 Fucbides. To these succeed thick deposits of black shale, 

 having no trace of organic remains. 



The strata which I have thus briefly enumerated, although 

 they form but an insignificant fraction of this immense series, 

 present matter for the consideration of the speculative na- 

 turalist. It has been seen that here occur many alternating 

 beds of Fucbides, and, probably, several species of these 

 fossil plants. Hence may be inferred the existence, at various 

 epochs, of so many separate surfaces, on which vegetation 

 flourished at the bottom of an ancient ocean. We thus ascer- 

 tain that, in those remote times, there were frequent successions 

 of these remarkable submarine plants, and many renewals of 

 the argillaceous surfaces upon which they took root. But it 

 does not appear that the consequence of these frequent 

 changes was the obliteration or destruction of the organic 

 forms of the vegetation so overwhelmed. The entire series, 

 from the lowest bed even to the highest, appear to retain their 

 original distinctness of outline. 



In the phenomena of deposition, and of recurring vegeta- 

 tion we may, perhaps, trace some circumstances analogous to 

 the formation of coal beds. 



The figure which illustrates this article represents a group 

 of Fucbides, on a scale somewhat less than half their actual 

 proportions [the drawing was about an inch too wide for our 

 page]. An assemblage of these groups, ornamenting the sur- 

 faces of large slabs, in clear relief, foinns one of the most i-e- 

 markable fossil productions of this continent. Imagine beds of 

 these Fucbides miles in extent, deposited, or rather accumu- 



