200 



quite uniform in its connposition, but exhibits slight variations in 

 the proportions of its principal constituents. 



The following results will serve to display its prevailing chemi- 

 cal nature, and the nioderate fluctuation of the several ingredients : 



Greensand of Thorp's Marl, Squankum. 



Description. — Colour, a dark olive-green ; granules of a mediunn 

 size; it composes 58-36 per cent, of the marl of the upper part of 

 the bed, and 72-36 per cent, of the lower. 

 Composition. — ^n 100 parts: 



Silica, - - - - 51-00 

 Alumina, . - - 6-50 



Protoxide of iron, - - 21-55 

 Potash, ... - 10-50 

 Lime, - - - - a trace. 

 Magnesia, - - - 1-08 



Water, - - - - 9-00 



99-63 



Greensand of Joseph Vandcrveef s Marl, Freehold, Monmouth 



county. 



Description. — Colour of the granules, rich green ; size, small ; 

 composes 70 per cent, of the upper part of the bed, and 92 per 

 cent, of the lower. 



100-00 



Greensand of the Marl of Poke Hill, near Plattsburg, Burlington 



county. 



Description. — Colour of the granules, a rich dark olive-green ; 



