662 NEW YORK STATE MUSEUM 



Migrating shore lines. Two excellent examples of a migrating 

 shore line are indicated by 1) the Stones river and 2) the 

 Oriskany and Onondaga invasions. The first, apparently, came 

 in from the south and west and progressed northwardly, reach- 

 ing the Mohawk and St Lawrence valleys just 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 rapidly and laying down 

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

 tion progressing apparently more slowly and laying down 

 the limestones of Onondaga age; and, meeting, their respective 

 faunas commingled in the Decewville formation described above. 



Effectiveness of folds as barriers to seas. The Green mountains- 

 Chilhowee barrier, the first and oldest fold west of the Appa- 

 lachian protaxis, 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 ineffective 

 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 (Helderbergian 

 barrier), lying to the west of the other two, still prevented the 

 Atlantic from joining the Mississippian sea throughout the time 

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

 however, was effected during late Oriskany, in Marcellus and 

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



The Mississippian sea crossed the Appalachian valley barrier 

 from southwestern Virginia northward to east central New 

 York, excepting the intervals when the north Atlantic by way 

 of the St Lawrence channel crossed it with the Normans kill 

 and Utica deposits and faunas, from Lowville to close of Frank- 

 fort time. Previous to this time, and immediately succeeding 

 the formation of the Appalachian fold, the Atlantic invaded the 

 terminal thirds of the Appalachian trough, filling the southern 

 Lenoir basin, which was confined between the effective Rome 

 and Chilhowee barriers, while it occupied two narrow basins in 



