THE ADIRONDACK GRAPHITE DEPOSITS 117 



There are no indications that the total depth to which the work 

 can extend is limited to 300 feet, hut as the dip undoubtedly will 

 increase in depth, which is especially true of the ore farther north 

 along the strike, the mining difficulties will increase. It is quite 

 possible that preliminary work could he conducted by quarrying the 

 ore along the strike from a point near no. 1 pit southward. 



The number of igneous rocks present on this property is not 

 absolutely known, but according to the present knowledge the 

 Algoman granite and the anorthosite are present. The latter rock 

 occurs as small bosses which have been severely squeezed so 

 that the rock resembles the crushed or " pulpy " phases of the rock 

 as shown throughout the Adirondacks. 



Farther away from the sedimentary rocks the amount of Gren- 

 ville admixture becomes less until a fine-grained granite makes 

 up the bulk of the rock exposed. This is in all probability the 

 Algoman granite. In this granite a large number of inclusions of 

 amphibolite occur in a manner quite similar to the inclusions found 

 in the so-called Laurentian granite of St Lawrence county. The 

 microscope points very clearly to the fact that these inclusions are 

 igneous and it is quite possible that they represent the ancient 

 metagabbro which Cushing believes to be the oldest eruptive in the 

 Adirondacks. If this is so, then they must be older than the 

 Laurentian granite ; and in view of the fact that the term Lauren- 

 tian is primarily applied to the older granite, the term pre-Lauren- 

 tian is used in the legend on the map of this property. 



Syntectic rocks. The valley is delimited on both east and west 

 by ridges composed of igneous rocks which present a number of per- 

 plexing problems that up to the present time have been only partially 

 solved. The relation between the Grenville rocks which occupy 

 the valley and the igneous rocks is apparently an eruptive one rather 

 than that they exist together by virtue of a fault. The east valley 

 wall is composed of a syntectic rock resulting from the assimilation 

 of Grenville rocks by an igneous magma. 



On the west, the transition from the sediments to the granite 

 can be traced much more satisfactorily. It is possible to recognize 

 the different forms for several hundred feet even though they have 

 been saturated by the solutions of the igneous rock. These blend 

 gradually into rusty assimilation products which give away in time 

 to the normal granite. 



The last igneous rock that is recorded in the region is the diabase 

 (olivine-augite-camptonite), tw'O dikes of which were found. One 



