towards the periphery of the concretion. Whether the calcite and other 

 mineral matter rilling these cracks, is derived from without, by infiltra- 

 tion, or from the concretion it: elf by segregation, is still an open 

 question. If the latter occurs, the processes of widening of the fissure; 

 byradial contraction of the rock mass, and of segregation of the mineral 

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

 open fissures. 



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

 are greenish grav in color, much less fissile than the pre- 

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

 embrace numerous layers 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 very poor in organic remains, no fossils 

 having been noted in them. They form the lower part of the 

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

 main section they 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 layer of calcareous concretions, or better a con- 

 cretionary bed of impure limestone, eight inches in thickness. 

 This probably- corresponds to J. M. Clarke's "Goniatite 

 concretionary layer,"* in as much as specimens of Goniatites 

 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 commonlv found in a very much compressed condition, 

 frequently perfectly flattened, and from having been replaced 

 by iron pvrites 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 Devonian faunas of Ontario County, N. Y, Pull. 

 16, 1', S, Oeol, Survey, 1885, p. 38 et seq. 



