246 E. T. Long — Minor Faulting 



bers of the Hamilton is a compound or slice fault devel- 

 oped on the south side of Stony Point some 25 miles down 

 Cayuga Lake. At this point a hard layer of limy shale, 

 much more compact and resisting than the surrounding 

 shale is sharply turned up at a 10° angle with dip to the 

 south. The faults occur just at the start of this high dip, 

 the greatest measured. For 200' along the shore south of 

 the point, the N 12° W joints show horizontal faulting 

 with displacement of 1" to 1%" of the joints of the E-W 

 system. The movement has pushed forward each succes- 

 sive block between two faults from west to east. That is, 

 the western part of the zone has not moved so far north 

 as the eastern part. The N-S joints dip west a few 

 degrees from the vertical but the angle was not measured. 

 It probably does not exceed three degrees as other joints 

 of the region which are not vertical show a dip very gen- 

 erally around 2°. The faulted area covers the entire 

 width of the shore as exposed at this point and may exist 

 over an even greater width and length. The rocks of the 

 whole point and near to it are broken up by an excessive 

 number of subsidiary joints at all angles and often much 

 curved. 



Mr. W. H. Bucher published an article on "The 

 Mechanical Interpretation of Joints," in the Journal of 

 Geology for December of 1920. To one not acquainted 

 with the laws of mechanics the "interpretations" sound 

 quite convincing. His main thesis is, that in brittle sub- 

 stances the lines of greatest pressure will bisect the acute 

 angle formed by the shearing planes. He then applies 

 this law to three areas, one of which happens to be the 

 Cayuga Lake region. Not being acquainted in person 

 with the area, he relies for his calculations upon the data 

 given in an article by Miss Sheldon. 9 His conclusions, 

 put into figures, being that the compressive forces, must 

 lie in a general N 35° E direction since this line must 

 bisect the angle between the two major joint systems of 

 the region, the average of the greater part of whose 

 angles will run at about N 74° E and N 5° W. This appli- 

 cation is here made to only the northern part of the area 

 which he discusses, but the results as stated are only a few 



9 Sheldon, P. ; Some Observations and Experiments on Joint Planes, Jour. 

 Geol., vol. 20, No. 1, 1912. 



