﻿REPORT OF THE DIRECTOR IQIO II 



fore been submitted to the Commissioners of the State Reservation 

 at Saratoga, has met their approbation and, if the means are pro- 

 vided, it may be hoped that the project will be carried into execution. 



The Precambric rocks of the Saratoga and Schuylerville region 

 have received special attention. These consist chiefly of two types, 

 syenites and rather uniform Grenville gneisses. There is but little 

 Grenville limestone. A comparatively thin band of quartzite which 

 locally is strongly graphitic, is worked for graphite at two localities ; 

 but the Grenville is mainly a white, or whitish, quartz-feldspar 

 gneiss, with pinkish garnets quite like the rock at Sprakers and on 

 the Little Falls quadrangle, and a very common rock in the Gren- 

 ville of the southern Adirondack border. The syenite cuts through 

 it in a series of comparatively small intrusions. In character and 

 in variations much of the syenite is very like the rock at Little Falls. 

 It becomes a coarse augen gneiss at its margins. 



There are a few diabase dikes which make up in size what they 

 lack in number. The great dike quarried just north of Saratoga 

 for road metal was followed northward for 12 miles to the ecige 

 of the quadrangle, and is capable of furnishing an enormous amount 

 of road material. 



The Northumberland volcanic plug on the Schuylerville sheet 

 was visited and carefully studied. Quarrying has rendered it much 

 easier of study than was the case ten years ago when Doctor Wood- 

 worth first described it. It has been faulted and a tremendous shear 

 zone cleaves it diagonally from base to summit. The nature of this 

 shear zone leads to the belief that the rock must have been under 

 considerable load when the shearing took place, and that the load 

 has since been worn away. Hence a considerable antiquity for the 

 plug is suggested. 



It was found necessary for the correlation of the " Hudson 

 River " shales of the Saratoga sheet to investigate first the Frank- 

 fort and L T tica beds of the Mohawk valley. This work indicates 

 that both the L T tica and Frankfort stages consist of two different 

 divisions. The lower one of the L T tica shale agrees in its fauna 

 with the lower third of the Martinsburg shale of the Appalachian 

 basin and is undoubtedly of upper Trenton age. It is therefore 

 separated from the typical Utica stage as Canajoharie shale. This 

 formation, to which much of the shale along the Hudson and in 

 Albany and Saratoga counties belongs, rapidly thins out westward 

 and does not reach the meridian of Utica. In the lower Mohawk 

 valley the remaining upper division of the Utica shale also differs 



