26 



THE GEOLOGIST. 



containing Stigraaria;, and in the overlying sandstone, or roof, 

 various specimens of ferns. Mr. Logan has Hkewise lately 

 made a series of independent observations on the carbonife- 

 rous deposits of North America, and Mr. Lyell announced 

 that that gentleman has found beds of fire-clay with stig- 

 marise under the coal seams of Nova Scotia. The Pottsville 

 district and the Lehigh summit mines were illustrated by 

 sections given to Mr. Lyell by Professor FL D. Rogers, who 

 has been engaged during five years in the Government 

 geological survey of Pennsylvania. The former section 

 extended from the north of Pottsville to the country ranging 

 immediately south of Orwigsburg. At the point where Mr. 

 LyelFs examination commenced, the coal measures are 

 vertical ; but, in an excavation from which the anthracite 

 had been removed, the bed occupying the position of the 

 underlay presented impressions of stems and leaves of 

 Stigmaria, unaccompanied, as usual, by any other plants, and 

 the stratum which represented the roof of coal contained 

 leaves of Pecopteris, reed-like impressions and Calamites, 

 To the south of these vertical measures is a deposit, inclined 

 ?X an equally high angle, of quartzose conglomerate, beds of 

 which alternate with seams of anthracite at the junction of 

 the two deposits. Proceeding further southward, there are 

 displayed successively — 1. Avast series of red shale, grey 

 sandstone, and red sandstone, which Mr. Lyell considers as 

 portions of the old red sandstone ; and 2. Olive coloured 

 shales, with Devonian fossils, the strata of the whole of 

 which are nearly vertical. Yet further south, and at a short 

 distance from Orwigsburg, the olive shales are succeeded by 

 highly inclined strata, assigned l^y Mr. Lyell to the upper 

 Silurian rocks, and through which protrudes an axis of beds, 

 considered by him to be composed of lower Silurian strata. 

 Lastly, on the southern confines of the section is a trough 

 of Devonian or olive coloured shales. The above geological 

 classification difters from that of previous observers, but Mr. 



