310 Schneider — Overthrust Faults in Central New York. 



course of the stream here, which change in the direction is no 

 doubt due in part at least to the existence of the fault right 

 here. 



Fault I. Dunlop's. — In making a cutting for Jamesville 

 branch of the Suburban railroad about two years ago, two some- 

 what similar faults were exposed in the calcareous layers 

 occurring three-eighths of a mile farther north. These layers 

 may be continuously traced to the northeastward until they are 

 found underlying the gypsum. They undoubtedly correspond 

 with the limestone ledge mentioned by Clarke as containing 

 the Lejierditia Scalaris Jones, which occurs in the Camillus 

 shale near the base of the Heard gypsum quarries. Inasmuch 

 as there is only a difference of five feet in elevation between 

 the altitude of these layers at faults I and II and faults 

 III and IV with practically horizontal layers between the 

 localities, it leaves little question but that faults III and IV 

 occur in this same Leperditia Scalaris limestone and not in 

 the Bertie. Fault 'No. I may be seen in the first cut show- 

 ing the limestone, which is about 150 yards south of the cross- 

 ing of the trolley and the Jamesville and Orville turnpike. 

 The thrust plane of the fault cuts these somewhat thinly lami- 

 nated layers, and dips at an angle of 35° to the south. The 

 layers show little disturbance except at the fault line. Second- 

 ary calcite crystals occur in the fractures of the limestone, 

 near the fault. 



Fault II Dunlojffs. — Occurs in the same formation and in 

 practically the same layers twenty yards south of fault No. I. 

 The thrust plane dips south 32° and the layers are bent for 

 several yards to the southward. The slickensided surfaces are 

 well shown, also a slight tendency toward slaty fracture. Cal- 

 cite crystals are lacking. The displacement is slight, probably 

 not more than three feet. The fault maintains its character 

 throughout the entire height of the cut. Owing to an accumu- 

 lation of talus and the dense vegetable growth the faults have 

 not been located on the west side of the stream. 



Other evidences of slight faulting are noticeable farther 

 north in this cut, also some shearing of the layers with the for- 

 mation of calcite crystals. 



The overthrusts now known and described in central New 

 York are — 



(a) Russell's Quarry at East Onondaga, fault plane cuts the 

 Manlius, Lower Helderberg, Oriskany, and Onondaga forma- 

 tions. Displacement forty-two feet. Also shown in Hibbard's 

 and adjoining quarries. Rocks affected for over a mile to the 

 eastward as shown by the marked slaty cleavage in the finer 

 grained limestones of the Corniferous. 

 ' Luther, " Econ. Geol. of Onon.," 15th Ann. Rept. K Y. 



