462 



Report of tup: State Geologist. 



the feldspar. Some of the cavities contain feldspar which has altered to 

 chlorite around the edges, while the centre of the crystal is a mass of 

 small green epidote grains. Another camptonite with a structure somewhat 

 resembling diabase, cuts the red gneiss northeast of Long pond near Monroe. 



A much sheared dike occurs on the east side of the road, one-half 

 mile north of the Sterling mine. The section shows a fine-grained ground 

 mass of a greenish mineral resembling serpentine, and small rods of feldspar, 

 mostly Karlsbad twins. There are also phenocrysts of a monoclinic feldspar. 

 Little can be said of the relations of this rock on account of its being so 

 decomposed. 



Quartz- Porphyry. A dike of this rock occurs in the Bradley mines. 

 The hand specimen resembled a fine-grained quartzite, but the section show s 



FlGUKE 25. Olivine-augite camptonite; showing 

 phenocrysts of olivine in a ground-mass of 

 plagioclase, granular pyroxene and magnetite. 

 (Specimen No. :J16.) 



Figure 26 Quartz-porphyry from Bradley mines ; 

 showing phenocrysts of zonal feldspar anil a 

 granular ground-mass of quartz and feldspar, 

 with shreds of decomposed mica and secondary 

 limonitc. (Specimen No :?54c.) 



a finely granular ground mass of quartz and feldspar, with shreds of decom- 

 posed mica and secondary limonite. The phenocrysts are monoclinal feldspar 

 showing a well developed zonal structure, the zones being a granular 

 decomposition product, probably serpentine. The occurrence of this dike is 

 unique, surrounded as it is on all sides by the more basic camptonites. 

 Quartz porphyries have not been hitherto recorded from the Highland 

 region of Orange county. 



Pleistocene Deposits. 



The pleistocene formations of the county consist of gravel and sand 

 deposits, boulders, clays, and lacustrine, as well as alluvial beds. There is a 

 drift mantle of varying thickness over the rolling country underlaid by the 



