GEOLOGY OF SARATOGA SPRINGS AND VICINITY II3 



thrust upon Ordovicic rocks as an extensive " carriage," is one 

 that is exceedingly difficult of solution on account of the intensely 

 folded condition of all the rocks involved and this condition is 

 the cause of differences of opinion. We differ from Dale in the 

 eastward extension which in our view this overthrust faulting 

 has attained. We have already above presented evidence that 

 some of the " outliers " of Ordovicic rocks on the Cambric 

 plateau are not such simple outliers, as claimed by Dale, but 

 " Fenster " (windows), that is, portions of the underlying but 

 younger Ordovicic rocks exposed by erosion, and the very small out- 

 lier of Ordovicic at Sudbury, under which Dale^ found Georgian 

 rocks can not be considered as vitiating the other evidence on 

 account of its small size (but 50 square meters) and nearness to 

 a larger Ordovicic body, which suggests that it may be but the 

 remnant of a small infolded mass, such as are apt to occur near the 

 Georgian-Ordovicic boundary on account of the contorted con- 

 dition of the rocks. Those '' Fenster," which we have in view, as 

 especially that connected with the Ordovicic shale belt of the 

 Hudson River plain by the Deep kill gorge (see page 112) lie 

 close to the western edge of the Georgian area, and indicate an 

 overthrust plane as far east as they extend. We see strong 

 evidence for the far eastward extension of the overthrust in the 

 appearance along the western edge of the Georgian area of such 

 rocks as the Bald Mountain limestone, which are totally different 

 from the rocks of the northern trough, and also lacking in the 

 broad belts of shales of the Western trough to the north and south, 

 and which therefore must have been brought a considerable distance 

 from the east, if we will not assume that the limestone was again 

 eroded over most of the area before or during the deposition of 

 the Normanskill shale, an assumption that seems supported by the 

 Rysedorph Hill conglomerate. 



The evidence which has been gathered by us in this relatively 

 small area, regarding the overthrust condition of the rocks, is in 

 full accord, as far as it goes, with the views expressed by Ulrich 

 in the Revision of the Paleozoic System, page 442, on the over- 

 thrust troughs in eastern New York and western New England. 



1 T. Nelson Dale. The Ordovician Outlier at Hyde Manor in Sudbury, 

 Vt. Am. Jour. Sci., 33:97- 1912. 



