TEANSACTIONS OF THE SECTIONS. 103 



work would commence there with a lower bed than was reached at the Norwicli 

 boring, namely the Kinimeridg-o clay, and, from the .absence of the next stratum 

 (the Coral-rag), and thinning-out and absence of others, he did not anticipate a 

 deeper bore than 1000 feet before coal would be obtained. 



On the occurrence of TrunJcs of Psaronius in an erect position, resting on thfir 

 origincd bed, in liocTcs of Devonian ar/e in the State of Neiu Yorlc ; with 

 some Inferences regarding the Condition of the Sea-hottoin and Shore-line 

 . dvring the Deposition of the Strata. By Prof. James Hall. 



During the year 1870 some excavations were made in Sclioharie County, N. Y., 

 in beds of sandstone, referred at that time to the upper part of the Hamilton group, 

 but which probably belong to higher beds in the series. Several trunks, apparently 

 of tree ferns, were found in an upright position, with their bases resting in and 

 upon a bed of claj^, in which they appear to have grown. In this clay, and in the 

 lower three feet of the sandstone above, there were abundant remains" of vegetable 

 substance, supposed to belong to these trunks and to other vegetation of the period. 

 Principal Dawson refers these trunivs to the genua Psaronius ; and he has determined 

 two or more species from the locality. 



The author believed that here we had evidence of a point of comparatively dry 

 land on the eastern margin of the De'^'onian sea. In tracing the beds westwards, 

 it was found that at first coarse sediment predominated with but few fossils except 

 plants ; but in going in a westerly direction the sandstones lose their coarseness, 

 the shales become finer and calcareous. A corresponding change takes place with 

 the fauna ; for at first, Avhere shells occur, they are chiefly those of the Lamelli- 

 branchiata, and it is not till we have travelled some distance to the westward that 

 Brachiopoda are found, at least in any quantitj'-. Where both occur, the Lamelli- 

 branchiata are confined to the harder and coarser beds, and the Brachiopoda, as a- 

 rule, to the finer sediments. Not only so, but sometimes the coarser beds are 

 charged with a few species of particular genera, as of Aviculopecten, while others 

 are crowded wdth 3Iodiola-Y\\e forms with few Aviculopectens ; whilst Gninuni/sia, 

 a genus which may perhaps belong to the Uuiouidiie, has sometimes flourished 

 abundantly, to the almost entire exclusion of every thing else. 



The changes here indicated can bo traced over a line of outcrop of more than 

 three hundred miles from east to Avest, and through a vertical thickness of from 

 two to four thousand feet. 



The author inferred that this area during the deposition of these beds was 

 undergoing continuous oscillation of level, with a general downward movement. 

 He considered that the alternation of coarser and finer beds, with their character- 

 istic fossils, might be due to such oscillating movements. 



On tJie Bclations of the Middle and Upper Silurian (Clinton, Niagara, and 

 Lower Jlelderherg) Rods of the United States. Bij Prof. James Hall. 



The author remarked that although American geologists still use the local terms 

 ai>plied to the various divisions of Palreozoic rocks by the Geological SurAey of 

 New York, yet the relations of these divisions to the greater divisions iu use in 

 England have been carefully studied. The grouping adopted by the author is as 

 follows : — 



TT o \ Lower Helderberg. 



Upper Siludian j Water-lime. ° 



Onondaga Salt gi'oup, or Salina formation. 



1 Niagara group. 

 Clinton group. 

 Medina Sandstone. 

 i Hudson-River group. 

 Black-lliver I Limestones. 

 Birdseye ) 



