312 Schneider — Overthrust Faults in Central New York. 



tlier west, but no facts are given, while the folds in the higher 

 formations are well shown in long arch at Cayuga Lake, and 

 similar undulations in strata at Seneca. Disturbances are also 

 noted by Lincoln in his account of the geology of Seneca Co.* 

 Inasmuch as most of the above mentioned disturbances 

 occur in or near the Helderberg escarpment, composed in the 

 main of heavy limestones aggregating several hundred feet in 

 thickness, and the persistence of the faults across central JNew 

 York, it would seem that all are the result of some considerable 

 force capable of affecting this entire region. In a general way 

 the solution of the salt from the Salina formation which imme- 

 diately underlies the Helderberg series has been regarded as an 

 explanation for all the disturbances in this vicinity. Mr. 

 Wheelock believes that the solution of all of the saline ingre- 

 dients of the Salina rocks together with the slight dip of rocks 

 of central New York is a sufficient explanation for the fault- 

 ing, as any settling of the layers must shorten the length of 

 the hypothenuse of the triangle and thus produce the force 

 which crumpled and fractured the rocks. The fact that the 

 softer shales sandwiched between the limestone bands are some- 

 times bent and sheared while the harder layers are not affected, 

 and that the larger throws all occur in the more resistant layers, 

 he believes will favor his explanation. This, however, would 

 be true irrespective of the cause, provided of course that it 

 were compression. It has also been suggestedf that expansion 

 due to the formation of gypsum would explain the faulting. 

 "While considering the causes of the faults it would be well to keep 

 in mind that there is a series of widely known intrusives which 

 parallel north and south this series of faults, and which extend 

 across the state from Little Falls on the east to Ithaca on the 

 west, and it is not impossible that both faults and dikes owe 

 their origin to the same general disturbance. The considera- 

 tion of this question, however, will be left to another paper. 



Syracuse, N. Y. 



*"Geol. of Seneca Co., " Kept. N. Y. State Geologist, 1894. 

 fE. H. Kraus, verbally. 



