towards ihc ijcriphciv of the concretion. Whether the caleite and other 

 mineral matter iilling these cracks, is derived from withonl, hy inliltra- 

 tion, or from the concretion itself b\' segres^ation, is still an o])en 

 qiication. If the latter occurs, the processes of widening of the fissures 

 by radial contraction of the rock mass, and of segregation of the mineral 

 matter are probably limullaneons, so that at no stage are there any 

 ojK'n fissiires. 



The Gray Naples Shales ( Cashaqtia shales).— These shales 

 itre greenish grav iti color, much less fissile than the pre- 

 ceding, and prone to weather into a tenaciotis clay. They 

 embrace numerous lavers of concretions, but in general these 

 do not exhibit the septarium structure. This is probably 

 due to the fact that the calcareous matter is more abundant 

 in these shales than in the black shales above, and hence 

 the concretions partake more of the nature of concretionary 

 limestone masses. 



The upper fifteen feet of these shales, while rich in concre- 

 tions, seem to be verv poor in organic remains, no fossils 

 having been noted in them. They form the lower ])art of the 

 vertical wall which terminates Philip's ravine, but in the 

 main section thev face the stream in a sloping, more or less 

 weathered and talus covered bank, supporting vegetation in 

 some places. Below this, at the base of the terminal wall of 

 Philip's ravine, and forming a prominent band in the main 

 section, is a laver of calcareous concretions, or better a con- 

 cretionarv bed of impure limestone, eight inches in thickness. 

 This probably corresponds to J. M. Clarke's "Goniatitc 

 concretionarv laver,"* in as much as specimens oiGonintitcs 

 are of common occurrence in it, usually forming the nucleus 

 of the concretion. Several species of Goniatites occur, but 

 thev are seldom found in a good state of preservation. They 

 are commonly found in a very much compressed condition, 

 frequently pei-fectly flattened, and from having been replaced 

 by iron pyrites which subsequently oxidized, much, if not all 

 of the structure is obliterated. The external form and 

 amount of involution therefore become the only characters 



*J. M. Clarke: On the higher Devoniau faiuuts of Ontario County, X, Y, Bull. 

 \Q, U. S. Geol. Swrvey, 1883, p. 38 et seq. 



