324 



BULLETIN OF THE 



a third cycle culminates in the Corniferous limestone, with deeper water 

 here than the second. The Marcellus shale, which follows abruptly, 



seems 



a change to shallow water or a neighboring shore ; the disappearance of 

 the limestone below it was more probably connected with a further 

 deepening of the water, or with a change in its temperature. But shal- 

 low water and near shore conditions came very clearly in the cross-bedded 

 Hamilton and higher sandstones, and even more distinctly in the Cat- 

 skill conglomerates. 



It is difficult to say what is here meant by "shallow water," for we 

 know too little of the winds and currents of these old times. But the 

 meaning of *' near shore" can be estimated from the Catskill conglom- 

 erates, the coarsest of the entire series here seen from the Hudson Kiver 

 upwards, and therefore probably nearer their source than any of the 

 other fragmental strata ; and yet the crystalline rocks from which their 

 pebbles have been chiefly derived cannot be less distant than the High- 

 lands of the Hudson (forty miles), the same series of rocks in Connecti- 

 cut and Massachusetts (forty), or the Adirondacks (sixty miles), for all 

 the intervening areas, even if then exposed to erosion, were of non- 

 crystalline rocks. " Near shore " does not, therefore, necessarily imply a 

 very close neighborhood to land ; and the carrying power of the paleozoic 

 currents must have been very cohsiderable. The identification of the 

 source of the Catskill conglomerate pebbles is an interesting and impor- 

 tant piece of work. 



Folds and Faults. 



The folds of small radius and varying form into 

 which the above-described strata have been pressed, and the strong in- 

 fluence of the rocks' attitude on the surface form, combine to render this 

 district an excellent training ground for Appalachian work. I know of 

 no Other where so many structural problems are as well shown within so 

 limited a space. Two well-known features are clearly seen : the folds 

 become more pronounced in going eastward, and all the anticlinals have 

 their steeper dips on the west. Points of special interest may be named 

 as follows. 



L 



The Catskill gorge from Austin*s Mill up to Leeds gives a very fine 

 series of natural sections. The railroad cutting and the lane leading up 

 from the mill to the turnpike give good evidence of the conformity of 

 the Hudson Biver strata under the limestones, and the Wateriime here 

 presents two interesting forms of distortion. The first is an unconform- 

 ity by horizontal faulting (fig. 3) ; the layers have been shoved past one 

 another on an oblique crack. ' It is worth noting that a similar style of 



n^^ f _ 



