REPORT OF THE DIRECTOR I9II 21 



some may rise directly along the fault, the probable source is be- 

 neath the slates to the east of Saratoga. The waters are believed 

 to be impounded beneath the tight slates and following up the dip 

 are tapped off near the fault. 



Artesian pressure from the northwest may aid their emergence 

 and probably dilutes their concentration. 



The mapping of the Schuylerville quadrangle which has been 

 carried forward by Doctor Ruedemann has presented extraordinary 

 difficulties as the region is .one where the essentially homogeneous 

 *' Hudson river shales " predominate and which the exactitude of 

 stratigraphy requires to be resolved into their essential units. The 

 Canajoharie, Snake Hill and Normanskill formations are all deter- 

 minable in this mass of shales and sands and have been now delim- 

 ited on the map. Along the eastern edge of the sheet the Georgian 

 formation, reaching in from the east and occupying the mountain- 

 ous region, and the belt of supposed Trenton limestone at the foot 

 of the mountains, were mapped. It was found that the Georgian 

 rocks are overthrust on an almost horizontal plane over underlying 

 rocks of later age, the Beekmantown, Trenton, Normanskill and 

 Snake Hill series. This style of mountain making involving such 

 tremendous overthrusting, though recognized in some other moun- 

 tain regions, has not before been determined as existing in the 

 Appalachian region of New York. 



In the " Trenton " limestones of this region a quite impressive 

 fauna has been found which indicates that the limestones are of 

 Fort Cassin age and the fault breccia (the latter both in its 

 pebbles and matrix) carries species of the Rysedorph Hill con- 

 glomerate near Albany, and is thus indicative of Atlantic origin in 

 contrast to the Trenton fauna of central New York and the west. 

 The Beekmantown beds are so distinct from those of the Champlain 

 valley that they will be provisionally termed the Bald Mountain 

 limestone. 



In the shale region of the Mohawk valley work was continued 

 in the resolution of the shale units which have been referred to as 

 the Canajoharie shale, Indian Ladder beds and the Snake Hill beds. 

 The two former terms were mentioned and defined in my report of 

 last year. The Snake Hill beds compose a thick formation of shales, 

 grits and cherts of lower Trenton age typically exposed on Snake 

 hill, Saratoga lake. The fauna and position of these shales indicate 

 that they overlie the Normanskill shales and probably belonged to 

 the eastern or Levis basin. In connection with this work has been 



