REPORT OF THE DIRECTOR AND STATE GEOLOGIST 1901 r!9' 



throughout this region is somewhat altered, but not more so at 

 Stark's Knob than remote from it. In the road on the south- 

 east of the knob, veins of calcite fill eavities of dislocation in 

 the slates and are probably to be referred to solfataric action 

 attendant on the irruption of the igneous rock in the neighboring 

 knob. This lack of contact metamorphism, unless such altera- 

 tion be limited to baking, which was not observed in the acces- 

 sible portion of the contact, and the failure of apophyses or 

 branching dikes are points of little value in determining the 

 origin of the igneous rock in the knob. It remains to determine 

 by other evidences whether the rock is intrusive or extrusive. 

 On the southeast side of the igneous mass and dissecting its 

 border are two faults; that on the eastern side strikes n. 9° e., 



Fig. 2 Cross section of Stark's Faob, showing general relation to the slates, and the 

 gross ball structure of the mass. 



that on the southeast, n. 51° e. The southeastern fault is 

 downthrown on the northwest, as on this side there is to be seen 

 the slate underlying a mass of trap on the southeast of the fault. 

 The complete relations of the igneous to the sedimentary rocks 

 on this side are not shown. Figure 2, which is a diagrammatic 

 representation of the cross section of the knob and its peculiar 

 internal structure, shows this fault, but the figure is purposely 

 drawn with some vagueness on the extreme left of the igneous 

 rock (pi. 4). 



To sum up the geologic relations of the Stark's Knob igne- 

 ous mass, it is surrounded on all sides by the Hudson river 

 slates. The principal mass is relatively faulted down into these 

 sedimentary rocks on the south and east. To the eye there 

 appears no distinct evidence of contact metamorphism; yet the 

 mass appears to be the superficial portion of a body which 

 extends downward into the slates and, from its general form and 



