REPORT OF THE STATE PALEONTOLOGIST I903 2O3 



One of the most noticeable differences between the upper Siluric 

 and lower Devonic formations of New York and Maryland is the 

 greater development of limestones with the corresponding less devel- 

 opment of shales in the latter region. In Maryland the clear water 

 condition allowing the deposition of limestone began in the Salina 

 and was continued almost without interruption to the Oriskany.^ 

 The Manlius fauna entered at the close of the Salina and continued 

 during a deposit of over a hundred feet of strata ; the land was, as 

 during the Coeymans, at a considerable distance from the present 

 exposed strata. During at least the upper New Scotland times, 

 land was not far distant from any of the five sections, but it either 

 soon sank again or a deflection of currents carried the muddy waters 

 in another direction, allowing the deposition of the Becraft. In 

 northwestern New Jersey and eastern New York, this was followed 

 by a return of the New Scotland conditions, during which the Port 

 Ewen was laid down. 



During the Oriskany the shore line was again nearer, so that the 

 deposit throughout the whole extent from Becraft mountain to 

 western Maryland is a silicious limestone. At the close of this period 

 the land rose both to the south and north. From the middle of 

 Pennsylvania southward through western Maryland, land conditions 

 existed, for the Marcellus rests on the eroded Oriskany ;2 but in 

 New Jersey and New York the shore line after remaining near dur- 

 ing a deposition of from 300 to 500 feet of the arenaceous shales of 

 the Esopus, again retired to some distance, producing clear water, 

 during which the heavily bedded Onondaga limestones were depos- 

 ited. That this submergence took place slowly is indicated by the 

 very gradual change from the Esopus to the Onondaga. 



It is interesting to note that chert is prominently developed in the 

 Coeymans and New Scotland in each of the five sections, i. e. from 

 Becraft mountain in eastern New York to western Maryland. 



Evidence of migration of faunas 



Favo sites helderbergiae praecedens occurs in 

 the lowest Manlius of western Maryland. In New York and New 



Schuchert. On the Lower Devonic and Ontario Formations of Maryland. 

 U. S. Nat. Mus. Proc. 26:413-24. 

 ' 1903. p.414. 



