r64 



NEW YORK S TATE. MUSEUM 



as a whole is of very uniform character, mostly a coarse grit, 

 white or buff in color, lying in quite massive beds which in 

 places weather into flags. Much of the rock is cross-bedded, and 

 the surfaces of many layers are ripple-marked. More or less 

 pebbly layers prevail throughout, though most notably at the 

 base. 



The bulk of the formation consists of pretty pure quartz sand. 

 There is considerable variation in thoroughness of induration 

 among the different layers, but the great mass of the rock is not 

 very porous, the interspaces between the quartz grains being very 

 thoroughly filled with secondary silica. Hence but few of the 

 layers are water-bearing. 



The thickness of the formation is unknown. The beds are 

 nearly horizontal, the prevailing dip being to the north and- 

 seldom reaching 5°, while in the majority of cases it is so slight 

 as to prevent accurate measurement. Dips changing from 

 northeast to northwest indicate the presence of extremely gentle 

 folds. The homogeneous character of the rock makes it im- 

 possible to follow individual beds for any distance and also pre- 

 vents the detection of the faults which are assuredly present. 

 The thickness is unquestionably great, but its determination 

 must await the evidence of the drill, and the recent boring at 

 Morrisonville, the only deep well ever put down in Clinton county, 

 has passed only part way through the formation. The record 

 will appear on a later page, but a thickness of 800 feet of Pots- 

 dam has been passed through with no indication of approach to 

 the base of the formation, so that the entire thickness may be 

 double that amount. 



The basal beds of the formation differ in character from the 

 main mass, much of the rock becoming coarse and pebbly and 

 some very coarse conglomerates occurring. Red is the prevail- 

 ing color for the finer grained basal beds, the more strongly 

 colored owing it to secondary deposition of iron oxid (hematite). 

 The basal beds are by no means as purely quartzose as the main 

 mass of the formation, feldspar (mostly red orthoclase) being 

 present in large quantity and in places much magnetite in addi- 



