﻿262 NEW YORK STATE MUSEUM 



i Explanatory record, 

 a Soil and glacial drift (surface to depth of 195 feet) 



Surface to 190 feet=sandis, gravels, clays of unusual variety 

 190-195 feet=reddish clay 

 b Residuary matter — mostly decayed rock (195-247 feet) 



212-240 feet micaceous clay — judged to be residuary because 



of the abundance of mica and the scarcity of worn quartz 



grains and rarity of foreign particles 

 c Decayed rock ledge preserving original structure 



representing interbedded limestone (247-377 feet) 

 247 feet=decayed rock ledge with white blotches showing 



traces of structure 

 256-330 feet=oxidized — mostly red and brown clays and sands 



from disintegration of decayed rock in place 

 349-351 feet— gray micaceous clay 

 251-377 feet=quartzose and micaceous disintegration sands 



and calcareous clays that effervesce in acid. Much pearly mica 

 d Decayed rock ledge representing Fordham gneiss formation 



(377-489 feet) — no calcareous matter 

 377-489 feet=quartz and pearly mica disintegration sand vary- 

 ing from coarse to fine and mostly of very light buff color 

 e Disintegration matter from a chloritized hornblendic gneiss of 



too little cohesion to withstand the grinding action of a drill 



of so small cross section (13/16 inch). (487-532 feet) 

 487-532 feet=fine dark colored disintegration sand composed 



chiefly of quartz, chlorite and mica, the material is of same 



composition as the cores secured just below 

 /. Core from more substantial rock — a hornblendic gneiss sound 



enough in part to withstand the drilling process and save a 



small amount of core (532-655 feet) 

 532-537 feet — 9 pieces of a green chloride foliated rock (14 



inches +) structure 70°-8o° — a close textured rock much 



oxidized and hydrated 

 537-551 feet — 8 small pieces and other fragments of same 



rock 

 551-566 feet — 17 pieces and several fragments same rock. 



All close texture and highly chloride 

 581-596 feet — 2 small pieces (two very brown, hard pieces) 



are probably not natural — " drillite," i. e. a peculiar product 



formed by the drill when it is run too dry and partly fuses 



fragments of rock and flakes of iron from the drill into a 



compact rocklike mass 



