EARLY DEVOXIC HISTORY OF NEW YORK AND EASTERN NORTH AMERICA 57 



Oriskany sandstone. This formation has a large development in the 

 northern part of the State, extending from Parlin Pond across the northern 

 end of Moosehead lake to Oxford Plantation. It may be several thousand 

 feet thick, consisting of various sandstones and slaty rocks, the latter often 

 exhibiting a cleavage at an angle with the strata. Parlin Pond shows the 

 fossils in great profusion. From this belt there have been recognized 

 Strop homena magnifica, S. rhomboidalis, Chonetes, 

 Orthis musculosa, Rhynchonella oblata, Strepto- 

 rhynchus radiata Van., Rensselaeria ovoides Hall, Lepto- 

 coelia flabellites, Spirifera arrecta, S. pyxidata, Lep- 

 todomus mainensis Billings, Platyostoma ventricosa Con., 

 Modiolopsis, Cyrtodonta, Avicula, Murchisonia, 

 Orthoceras, and Dalmanites. A fucoid allied to the Fucoides 

 cauda-galli occurs on Moosehead lake. We have as yet few details of 

 the distribution of the formation. It is best developed near Parlin Pond, 

 the most southwestern exposure seen. The fossils were determined by E. 

 Billings, of Montreal, P. Q. 



Recent explorations have been directed towards the southwestern 

 extremity of the terrace, as it points towards New Hampshire. The country 

 between Moosehead lake and Parlin Pond, as well as that further south- 

 ward, was traversed, and it was found that the Oriskany group, with a 

 thickness of 2880 feet, rests against Eozoic gneisses and granites. 

 Towards the southwestern end there were no indications of the passage of 

 the sandstones into crystalline schists manifested. Hence two conclusions 

 were derived from the facts observed : 



1 The Oriskany sandstone reposes gently upon Eozoic gneisses 

 the first bearing scarcely more traces of alteration than the corresponding 

 group in New York, while the second seems to have been metamorphosed 

 and elevated before the Devonic formation was deposited. No further trace 

 of this group has yet been found towards the White mountains. It has 

 been followed through Maine from 150 to 200 miles, and similar rocks are 

 described in Nova Scotia by Dawson. It can, therefore, no longer be 

 maintained with reason that these strata pass into New Hampshire in a 

 metamorphosed condition. 



2 The Oriskany is several times thicker than in its extension in the 

 interior and farther south in Pennsylvania. The greatest thickness men- 

 tioned by H. D. Rogers, is 520 feet, only one fifth its dimensions in Maine. 

 The greatest observed thickness in New York is only 30 feet. 



The enormous thickness ascribed to this series of arenaceous beds is 

 entirely borne out by Mr Nylander's measurements and it appears that the 

 basin in which these sediments have been deposited was bounded by very 

 old strata extensively crystallized and to have had a much longer existence 



