120 PROCEEDINGS OF THE BOSTON MEETING 



Hatch shales rise to 1,255 feet in the gullies and no Nunda sandstone appears 

 on the hilltops in outcrops up to 1,500 feet or over. An excessive west dip, at 

 least 100 feet per mile, is required to explain this without faulting, and the 

 downthrow is on the west, as in the broken limestone scarps to the north. 



An earlier observation on this line of disturbance was made by Mr. D. W. 

 Williams, geologist for the Dominion Natural Gas Company, and his assistants, 

 who recognized the westward plunge in the Centerfield (a Hamilton) lime- 

 stone^" halfway between East Alexander and East Bethany (see map) and 

 located an exploratory drilling on it. Five miles north, near Batavia, accord- 

 ing to Mr. H. P. Woodward, are the locally famous "Seven Springs." The 

 latest development along this line is an infall sink in the Salina shales near 

 Byron, New York, investigated by the writer for the Director of the State 

 Museum, which may or may not have genetic connection with the supposed 

 fault. 



Nature and Origin 



This displacement is, of u:ourse, an unexpected phenomenon in the llat- 

 lying Paleozoic strata of western New York. It is 135 miles west of the 

 nearest known large faults, at Clinton and Trenton. An abundance of small, 

 apparently superficial faults, often with accompanying buckling, proves to 

 exist between Rochester and Lake Erie, but the only other one found of 

 mappable size, offsetting formations, is a broad overthrust discovered by 

 D, W. Williams in the Laona-Shumla beds near Smiths Mills, Chautauqua 

 County, with a throw of 25 feet and a heave of possibly 100. Scarcely any 

 square mile is wholly free from these small displacements — either buckles, 

 normal faults, or flat thrusts — but they are easily ascribed to surface agents 

 or to removal of subjacent salt or gypsum, etcetera. The Clarendon-Linden 

 fault involves beds far below the salt, belongs in another category, and is 

 clearly of tectonic origin. Its isolation makes it unique in New York geology 



EXPERIMENTAL STUDIES ON THE FORMATION OF JOINTING PLANES 

 BY FRED E. WRIGHT 



(Ahstract) 



Slabs of polished plate-glass one to two inches thick, if chilled rapidly, 

 develop fracture cracks which have all the characteristics of platy and colum- 

 nar jointing in lava -flows ; the strain phenomena and consequent jointing 

 cracks can be studied on these plates in actual process of development and 

 photographed in polarized light with a moving-picture camera. The fracture 

 planes formed under these conditions of rapid cooling are entirely different 

 from those which appear on rapid heating, which produces curved fracture 

 planes not unlike the warped exfoliation surfaces of natural rocks. 



An analysis of accurate measurements of the strains set up in glass plates 

 for different temperature gradients leads to interesting conclusions, which are 

 significant in the general theory of fracture phenomena in rocks. 



Presented with illustrative experiments, without notes. 



10 Defined : Clarke and Luther, Bull. 63. N. Y. State Museum, pp. 17, 19, 50. 



