SERPENTINE AT E ASTON 427 



One point more should be mentioned regardini^ the occurrence 

 of the tremoHte beds in the Anthony's Nose granite area. After 

 the formation of the fault AB, which cut diagonally across the 

 pre-Cambrian ridge, the two dislocated ends, viz., Chestnut Hill 

 on the southwest and Marble Mountain on the northeast seem 

 to have been thrust b\^ each other along the fault plane AB, 

 the tremolite beds as well as the Anthony's Nose granite on the 

 southeastern slope of Chestnut Hill being made to override the 

 under thrust end of Marble Mountain in a series of thrust faults 

 by which the tremolite beds became faulted in between granite 

 walls, while the tremendous shearing to which the rocks were 

 subjected brought about the alterations which have been de- 

 scribed. That there has been crustal shortening in a direction 

 at right angles to the principal folding is shown by a series of 

 more or less parallel faults running at right angles to the series 

 already described. In the southern limits of the city of Phillips- 

 burg are two thrust faults which hade to the east, and which 

 bring the pre-Cambrian gneisses to the surface in two masses 

 separated by about thirty feet of post-Algonkian dolomite. The 

 Pennsylvania Railroad in traversing this mass has blasted all the 

 way through in the dolomite, being the line of least resistance, and 

 leaving either wall of the cut as gneiss. Two other faults cut- 

 ting at right angles across the southwestern end of Chestnut 

 Hill can be made out. The force producing this transverse 

 series of faults could be called into requisition in explaining the 

 thrusting by each other of the dislocated ends of the Chestnut 

 Hill ridge and at the same time the curved branching thrusts 

 which intersect the granite. 



Lafayette College, Easton, Pa., January, 1900. 



