ABSTRACTS AND DISCUSSIONS OF PAPERS 101 



SOME STRUCTURAL FEATURES IN THE QREEN MOUNTAIN BELT OF ROCKS 



BY C. E. GORDON 



(Abstract) 



The Taconic, or, more broadly speaking, the Green Mountain belt of rocks, is 

 notably, if not preeminently, a region of fracture. The great displacements 

 are genetically of the reversed type, although in later adjustments there may 

 have been some normal faulting along the planes of earlier reversed faults. 

 These great fracture lines follow the general trend of the Green Mountain 

 axis, but often cross it. An east-west trend of the foliations of the ancient 

 gneisses, which has been observed at certain places, may be genetically asso- 

 ciated with these transverse breaks if, as seems likely, the lines of weakness 

 in these basal gneisses coincide with their structural features. 



Erosion has been extensive enough to expose the faulted relations of the 

 gneisses and the younger rocks. A reasonable restoration of the Precambrian 

 floor on the basis of this faulting gives a different impression of the topog- 

 raphy of the land over which the Cambrian sea transgressed from what the 

 present topographic relations, viewed without recognition of the extensive 

 fracture of the basal Precambrian floor, might convey. 



Presented by title in the absence of the author. 



FAULTING IN NORTH-CENTRAL KENTUCKY 

 BY ARTHUR M. MILLER 



Faults which are all of the normal type, with prominent drag zones on their 

 downthrow sides, are by no means uncommon in the Blue-grass region of the 

 State, though, on account of the length of time which has elapsed since they 

 were formed and the great thickness of residual soil covering, they are not 

 always easy to detect in the uplands. 



They vary in length from a few hundred yards to nearly 50 miles, and in 

 throw from 5 or 10 to 350 feet. 



They nearly always occur in pairs — a primary and a secondary fault — the 

 latter evidently consequent on the former. 



The adjustment of tension strains accompanying a bowing up of the Cin- 

 cinnati Geanticline might well result in slippings along tension fissures. Such 

 would constitute the "primary" faults. The dropping down with tilting in of 

 the strata toward these faults would tend to develop parallel tension cracks 

 at certain distances away from the primary cracks. A further slipping and 

 tilting of the strata with the continued bowing up of the anticline would widen 

 and deepen the developing secondary fissures until they, too, would become 

 planes of slipping, constituting "secondary" faults, and the wedges of strata 

 between the primary and secondary would become "fault-blocks." 



This type of faulting is well illustrated in the West Hickman Creek fault 

 strip, which stretches from near Paris, in Bourbon County, to near Union Mills, 

 in Jessamine County, a distance of 25 miles. 



The maximum throw near the middle of the strip of the west (primary) 

 fault is about 150 feet. Nearly its whole extent is in the uplands of the 

 Central Blue-grass region, where it displaces Eden shale on Lexington lime- 



