26 NEW YORK STATE MUSEUM 



In the old quarry on Ides hill ancient faults are well marked by 

 slickensides in the bedding planes showing that this movement 

 is by no means a recent one. 



Postglacial faults in New Hampshire. Prof. C. H. Hitchcock 

 reports a case of postglacial faults in slates on the summit of 

 Kilburn's Crag, near Littleton, N. H. 1 He states that " seg- 

 ments of the slate have been crowded up (or down) a quarter 

 of an inch since the glaciation was effected. When made the 

 smoothing must have been continuous; now one part of the 

 ledge, with the striae upon it, is a quarter of an inch higher than 

 what is adjacent, and the change is abrupt. These jogs in the 

 ledge are small faults made by the same crowding from one side 

 that has lifted up the mountains." He supposes such cracks to 

 have been accompanied by earthquake shocks, intimating that 

 the total movement took place at one time. 



In a letter to the writer dated June 19, 1905, Professor Hitch- 

 cock states that as he recalls the faults at Kilburn Crag their 

 course is nearly east and west and the downthrow on the south 

 side. 



General conclusion 



The detailed observations given in this paper, sligh't and incom- 

 plete as they are, show that the change of level or the so called 

 tilting of the land in and about the New England district since 

 the retreat of the Wisconsin ice sheet has been accompanied by 

 the fracturing of rocks in certain zones of structure presumably 

 so disposed as to yield to stress by small repetitive faults mainly 

 with a downthrow to the northwest in structures whose strike 

 is northeast and southwest, and with a downthrow mainly to 

 the south in structures whose strike is nearly east and west. 

 While the throws as pointed out appear from the reports to be 

 on the whole greater along the northern borders of New England 

 in the field described by Matthew and Chalmers than on the 

 south in New York and while at the same time the examples 

 from the interior of New England so far reported also favor the 

 view of uplift on the north and downthrow on the south, the 

 examples so far known are too few to warrant drawing the con- 

 clusion from them that the degree of faulting is commensurate 

 with the extent of the tilting and change of level. Wherever 

 we have full evidence of the nature of the faults they appear to 



1 "Tbe Geology of Littleton, New Hampshire," reprinted from History of Littleton, 1905, 

 p. 28-29. 



