HUDSON RIVER BEDS NEAR ALBANY 519 



xone, and it is possible that it is continuous with similar beds of 

 lower Trenton age exposed along the lower Vlaumans kill. Un- 

 fortunately no outcrops could be found along the middle andi 

 upper courses of the Coeymans and Vlaumans kills. 



No other exposures of Lorraine beds have been found in the 

 investigated area. Their distribution to the northwest, west and 

 southwest of Albany is evidence of the restriction of the Lor- 

 raine beds to the western part of the area. 



Prof. Prosser has lately separated the Utica and Lorraine 

 ehales of the lower Mohawk valley by testing them with HCl, 

 with which reagent the calcareous Utica shale will strongly ef- 

 fervesce, w^hile the Lorraine shale does not react. This test had 

 not suggested itself to the writer when in the field; but, on later 

 application to the shales of the various terranes of the Hudson 

 valley region near Albany, it was found to fail in the clastic 

 rocks of this region, where even the Trenton is represented by 

 argillaceous shales, and among the Utica shales only those from 

 the penitentiary at Albany were found to effervesce, while all 

 specimens of Utica shale from various localities of the Mohawk 

 valley subjected to this test by the writer have strongly reacted. 

 This indicates the great change in the marine conditions from 

 west to east in this region throughout a long period. 



B UTICA BEDS 



East of this area of Lorraine rocks, the presence of a zone of 

 Utica shale extending in the direction of the general strike of 

 the shales of the Hudson river valley, has been established by 

 the finding of 15 outcrops which contain Utica shale fossils (Com- 

 pare the accompanying map). 



Station 5. Mechanicsville 



The excavation of a large spillway for the establishment of the 

 Hudson light and power company of Mechanicsville, on the Hud- 

 eon, about 2 miles below Mechanicsville, offered a rare opportunity 

 for collecting in the shale. Thongh this locality lies several miles 

 north of the boundary of the area investigated thus far, it was 

 thought expedient to include its description in thifi paper, as the 



