﻿204 NEW YORK STATE MUSEUM 



greater proportion of the recovered pieces are comparatively solid 

 even where the total percentage of saving is very low. It is evi- 

 dent that some of the core, a considerable percentage, has been 

 ground to pieces in the process of boring. This is especially notice- 

 able at hole no. 40. 



Hole no. 40. Much trouble has been met in this hole. A 

 careful analysis of the record and core and the behavior of the drill 

 is interpreted as follows: 



1 Partially assorted drift, chiefly sand and gravel was penetrated 

 for 125 feet. 



2 Limestone bed rock of fairly sound quality was struck at 

 about 125 feet (about el. -40). 



3, The casing that was put down to shut out the sand failed to 

 reach solid rock, and this permitted a continual supply of pebbles 

 and sand to run into the hole and obstruct the work with each pull 

 up. The presence of these pebbles was also instrumental in grinding 

 the core to pieces, and this accounts chiefly for the low saving. 



4 After this opening was plugged up with cement, the drilling 

 was continued successfully until a somewhat broken quartz vein 

 was encountered and this has been followed for about 35 feet. Its 

 broken condition afforded another opportunity for fragments to fall 

 into the hole, and on top of the drill, bringing the work for a second 

 time to a standstill. It is certain also that the drift pebbles still fall 

 in. As the formation stands vertical here it is not surprising that 

 any feature should show an apparent extent quite out of proportion 

 to the real value. The quartz vein is probably of no great breadth. 

 Small seams containing mud may also be followed 15 or 20 feet 

 and still be of no great significance in the formation as a whole. 

 The rock fragments (core) recovered in this hole are fairly sound. 



5 In spite of the many delays and difficulties of this hole, it is 

 apparent that the general rock formation is not responsible for it 

 all. The failure to reach solid rock contact with the casing has been 

 the cause of part of it. Later the penetration of a rather rare 

 quartz vein, a thing that would not often be found in the limestone, 

 has added to the trouble. Both of these causes are so rare that 

 they may almost be given the value of accidents. 



But the last 100 feet or more of the hole, from depth 225 feet to 

 335 feet, shows an unusually questionable condition. Only a few 

 rock fragments are saved and they include limestone and quartz 

 vein matter. The rest is wholly disintegration sand of rather com- 

 plex composition but carrying very much mica. This is all wash 



