288 H. p. GUSHING — FAULTS OF CHAZY TOWNSHIP, NEW YOKK. 



abound, in general folds are absent. This is true in a marked degree of 

 the region at the lower end of the lake. At the upper end of the lake 

 in Vermont, as the line of the great thrust fault is neared, the rocks are 

 found to be folded as well as faulted.* Aw#y from this vicinity, how- 

 ever, folds do not appear, or else are extremely gentle. In each fault- 

 block the dip is steadily and persistently in one direction, and the vari- 

 ous strata follow one another in regular order with n# repetition. 



FEATURES AND CLASSIFICATION OF THE FAULTS. 



In none of the faults occurring in Chazy township is the fault-plane 

 itself open to inspection. Elsewhere on lake Champlain, however, fault- 

 planes are visible, and when this is the case they are seen to be nearly 

 or quite vertical. Attempts to determine the hade of the Chazy faults 

 geometrically give very unsatisfactory results, because data of sufficient 

 precision are not to be obtained, but an approach to verticality is sug- 

 gested by them without, however, indicating whether such hade as exists 

 is to the up or the down throw. There is at the present time no evi- 

 dence at hand to show that in respect to hade and throw there is more 

 than one class of faults in the region. 



In going from end to end of lake Champlain a succession of faults 

 produces a frequent repetition, in whole or in part, of the lower Paleozoic 

 series. Locally many faults have been mapped, but no attempt has as 

 yet been made to trace the faults from one place to another in order to 

 determine their extent. It is indeed questionable whether this is possi- 

 ble in any considerable measure. In that portion of the region directly 

 under consideration the faults may be conveniently grouped in three 

 classes, but there is as yet no evidence that this grouping may be applied 

 to the region as a whole. For the purpose of description, they may be 

 referred to as of the first, second and third classes, and the considera- 

 tion of their differences will more appropriately come in after the faults 

 themselves have been described.f 



FAULTS OF THE FIRST CLASS. 



Fault A- A. — The most pronounced structural feature in Chazy town- 

 ship is the great fault whose position corresponds closely with the line 

 of Tracy brook from a point one mile north of West Chazy village, where 



*See Brainard and Seeley: Bull. Am. Mus. Nat. Hist., vol. iii, no. 1, pp. 8, 9. 



t Some references to faults in other parts of the Lake Champlain region are appended. The 

 list makes no pretense of being complete. 

 E. Emmons : Geol. of New York, vol. ii, p. 274. 

 Brainard and Seeley: Am. Geologist, November, 1888, p. 326. 



Brainard and Seeley: Bull. Am. Mus. Nat. Hist., vol. iii, no. 1, pp. 5, 8, 11, 15, 18, 21. 

 C. D. Walcott : Bull. 81, U. S. Geol. Survey, p. 344. 

 T. G. White : Trans. New York Acad. Sci., vol. xiii, p. 225. 



