308 Schneider — Overthrust Faults in Central New York. 



Art. XXXIY. — Preliminary Note on some Overthrust Faults 

 in Central New York y by Philip F. Schneider. 



My attention was recently called to two unrecorded over- 

 thrusts in the limestones of this vicinity by Mr. Charles E. 

 Wheelock, who discovered the same, and at whose request this 

 preliminary notice has been prepared. In company with Mr. 

 Wheelock the writer recently visited the locality and this 

 description is largely confirmatory of Mr. Wheelock's observa- 

 tions, which will be given in full in a future paper. 



These disturbances in the horizontally stratified Paleozoic 

 rocks of central New York, where for so many years it was. 

 thought they could not exist and where the first announce- 

 ments of such occurrences were received with such incredulity, 

 are not yet sufficiently common to permit them to pass unre- 

 corded. The faults are furthermore important because of the 

 relation between them and the well known peridotite intrusives 

 and the probability of the identity of the causes producing the 

 same. 



Both of the faults brought to light by Mr. Wheelock occur 

 in some thinly bedded limestones which he correlates with the 

 Bertie dolomite as described by Clarke in his recent report on 

 the formations in the Tully Quadrangle,* or with the lower 

 layers of the Waterlime of Yanuxem,f Geddes,^; Schneider,§ 

 and Luther. || 



The faults can be easily studied in the gorge of Butternut 

 Creek, near Dunlop's station, one and one-quarter miles north 

 of Jamesville. In the east cliff, a few yards to the south of the 

 stairs leading from Fiddler's Green to the gorge of the creek, 

 the thrust plane of the southernmost of the faults (Fault IY. 

 Dunlop's) can be easily distinguished as it extends upward 

 from the base of the cliif through its entire height, a distance 

 of nearly thirty feet. At this point the cliff is comparatively 

 free from talus. The dip of the fault plane is 28° to the north- 

 east, N. 40° W. This northerly dip of the thrust planes of both 

 of the faults located by Mr. Wheelock is interesting inasmuch 

 as they seem to belong to a series of faults extending in an east 

 and west direction across the country, which hade to the south- 

 ward. If It is furthermore surprising as they occur about mid- 



* Bulletin 82, N. Y. State Museum, 1905, J. M. Clarke. 



f Rept. 3d Dist. N. Y. 1842. 



% Geol. Survey of Onon., Eept. N. Y. State Agricultural Society, 1859. 



§ Notes on Geol. of Onondaga Co., N. Y. 1893. 



|| Econ. Geol'. of Onon., 15th Ann. Rept, N. Y. State Geol. 1895. 



•[[ This refers to the overthrusts in the Helderberg limestone series only and 

 not to the slips and slides which are so common in or near the gypsum beds, 

 and which can be explained by the expansion due to the formation of the 

 gypsum, or to the solution of the gypsum or salt immediately underneath. 



