54 NEW YORK STATE MUSEUM 



general character, the rock strongly resembles the variety described 

 above along the Spackenkill road on the farm of Mr Mulkemus 

 near the eastern margin of the belt. No fossils were found in the 

 beds of this quarry and hence no definite idea of its age could be 

 obtained. 



Just east of Camelot station, as described above, arenaceous lime- 

 stone identical with that in Ruppert's quarry, dips to the south at 

 an angle of 12°. This suggests a southward pitch and a superior 

 position for the strata in the Stoneco quarry, a mile to the south 

 of Camelot. 



The stratigraphic position and estimated thickness of the Stoneco 

 beds agree with those of the cherty rocks along the Spackenkill 

 Foad to the northeast. Presumably these strata once entirely 

 covered the Upper Cambric (Potsdam) along the central and 

 western portions of the strip and have been preserved at the south 

 on account of the pitch of the series. 



Structural features. It is not possible to tell with absolute 

 certainty what the exact relationships are among the different strata 

 composing the series of this western strip. Presumably the Upper 

 Cambric beds are followed conformably by those which apparently 

 have a suj^erior stratigraphic position. But in these latter strata 

 it is necessary to recognize a probable interval of erosion as is in- 

 dicated by relationships which can be determined with more exact- 

 ness within the central strip and which is shown by the presence 

 of a conglomeratic layer, even in this western belt. As will be 

 discussed farther on this conglomerate, though possessing peculiar 

 features, marks a change in fauna as well as in the lithic character 

 of the rock and must be taken as marking a definite hiatus. 



The present almost horizontal position of the Upper Cambric 

 and overlying beds theoretically admits of two explanations. It 

 either represents a close overturned, recumbent fold, or else a 

 reversed fault accompanied by westward thrusting, which was pre- 

 ceded by only relatively little folding. 



These rocks show no indications of extensive slickensiding, of 

 compression of layers, or of flow structures such as would be ex- 

 pected in violently folded strata. There is evidence of some brec- 

 ciation and slipping in the rock along the eastern margin, but this 

 is not severe. There is extensive fracturing which is, however, 

 readily explained by the hypothesis of reversed faulting and thrust- 

 ing. 



The field relations point to an upward movement of older strata 

 into overlying younger ones similar to that already described for 



