r98 NEW YORK STATE MUSEUM 



of Green hill. The prospect has been opened where a thin band 

 of limestone is in contact with gneiss. The " bluestone " which 

 yields the best return is a greatly decomposed limestone. 



Perfectly regular and continuous bands of dark rock are also 

 common in the limestone. These are from 1 to 2 inches wide. 

 They run at times for 20 or 30 feet parallel to each other, and 

 6 to 8 inches apart. They are well seen in the white graphitic 

 limestone half a mile from Minerva on the road to Irishtown. 

 They consist essentially of hornblende and feldspar. The horn- 

 blende is in large rounded crystals, colored dark bottle green. 

 It is strongly pleochroic and but little broken up by cleavage 

 cracks. Occasional hypersthene is the only other dark silicate. 

 With these are associated orthoclase and often abundant plagio- 

 clase. This rock is invariably found with the limestone, and it 

 carries garnet at times. A prospect hole for garnet on the hill 

 southwest of Oalahan pond shows limestone above as a hanging 

 wall, with the hornblendic rock containing large lenses and 

 rounded masses of garnet as the footwall. Here several tons 

 have been broken out, but, though the garnet is of good quality, 

 it is not found in quantity sufficient to justify further explor- 

 ation. It is on the contact between the hornblendic rock and 

 the limestone that we can best determine the special rela- 

 tions of the limestone. It is found to vary but little from n. 

 30 w. to n. 50 w. on the strike. The dip is from 20° to 80° to 

 the northeast. The limestone frequently shows minor folds. 

 A small anticline with axis n. 52 w. is found on the west bank 

 of the Hudson, half a mile below the mouth of Cedar river. 

 Along the bank of Minerva stream, where the road crosses 

 leading east from Olmstedville, the limestone is exposed, over- 

 lain by the hornblendic rock and so folded as to give a gentle 

 syncline and two sharper rolls. The exposures of crystalline 

 limestone are often so massive as to show but little or no trace 

 of the former bedding planes, and again they are visibly con- 

 torted. This is well seen south of Black Pond mountain. The 

 brook just north of the road and parallel with it at this point 

 runs part way on gneiss (strike n.49 w.,dip 21 n. e.) but at the con- 



