G(>2 XBW YORK STATR MTSKUM 



Migrating shore lines. Two cxccllcnl cxjunplrs of a iui»jratiug 

 shori' line are indicali'd l»v 1) the Stones river and 2) the 

 Oriskany and Onondaj^a invasions. The first, ai)i>arently, came 

 in from the sonth and west and progressed northwardly, n^ach- 

 ing the Mohawk and St Lawrence valleys jnst before the close 

 of the Stones river, the last division of that age being almost 

 uniformly represented there by the Lowville limestone. 



The second invasion was very different from that of the Stones 

 river. It came in from both the Atlantic and the southwest, 

 that from the former source advancing lajudly and laying down 

 the coarse dcjtosits of the Oriskany, that from the latter direc- 

 tion jM'ogrcssing api>arently more slowly and laying down 

 the limestones of Onondaga age; and, meeting, their resi)ective 

 faunas commingled in the Decewville formation described above. 



Effectiveness of folds as barriers to seas. The Green mount ains- 

 C'hiiliowee barrier, the tirst and oldest fold west of the Appa- 

 lachian i>rotaxis, was not crossed by the sea from the close of 

 the Beekmantown age to early Siluric time, but through the 

 whole of Siluric and some of Devonic time it was inefifeetiv(» 

 as a barrier to the Atlantic, which passed over it probably in 

 the region of Maryland. These same waters also crossed the 

 Appalachian valley barrier, but a younger fold (Ilelderbergian 

 barrier), lying to the west of the other two, still i>re vented the 

 Atlantic from joining the Mississij>pian sea throughout the time 

 from Medina well into the Oriskany. Tlu' union of the two seas, 

 however, was elTected during late Oriskany, in M;ncellus and 

 possibly again during a portion of Portage time (Genesee). 



The Mississippian sea crossed the Appalachian valley barrier 

 from southwestern A'irginia northward, to east central New 

 York, excej^ting the intervals when th(» north At hint ic by way 

 of the St l.awrenee cliannel crossed it with the Normans kill 

 and T^tica deposits and faunas, from Lowville to close of Frank- 

 fort time. Previous to lliis lime, and immediately succeeding 

 the formation of tlie Ajipalathian fold, IIh' Atlantic invaded the 

 terminal thirds of ilie A])|ialachian trough, tilling the southern 

 Lenoir basin, which was confined between the effective Kome 

 and ('hilhowee barriers, while it occupied two narrow basins iu 



