233 



or black ; when dry a light blue, or gray. The lighter kind con- 

 tains more clay, which is of a dove-colour, and sometimes of a 

 light gray. The tint of the grains is a dark olive-green, almost 

 black, and in this quarter rarely a light green. Sometimes the 

 clay exceeds in quantity the green grains, and this in marls which 

 are regarded as being very active. Those varieties which 

 possess the lowest reputation are found invariably to contain 

 either a quantity of siliceous sand or mica. 



The fossils are Exogyra costata, Gryphea convexa, G. muta- 

 bilis, Ostrea falcata, Belemnites Americanus, Terebratula, Spines 

 of Cidaris, Teeth of Shark, and Vertebrae of Crocodile. 



When the marl dries, the surface is sometimes covered with a 

 white or gray incrustation. When moist, the black marl often 

 exhales a sulphurous odour, and the white efflorescence has an 

 astringent sweetish taste, indicating it to be in part at least, a 

 sulphate of alumina. 



The marl in this quarter has been known and used as a fer- 

 tilizing agent for forty years. It is applied very profusely ; one 

 hundred loads to the acre, or even more, being no unusual 

 dressing. The improvement to the soil is very permanent, chang- 

 ing the natural growth from Indian grass and jive finger, (or 

 cinquefoil,) to fine white clover. White alder and other plants 

 of rich soils abound in the meadows. 



The natural timber of this, as of most other parts of the marl 

 tract, consists of several varieties of Oak, also Chestnut, Locust, 

 Beech, Maple, Dogwood, Hickory, Liriodendron or Tulip Pop- 

 lar, &c. 



The following analyses exhibit the composition of the mar! in 

 this vicinity : 



Analysis of a Marl, {the upper stratum,) from the farm of John 

 Smock, Freehold township, Monmouth county. 



Composition. — In 100 parts: 



Greensand, - - - 90-00 



Coarse siliceous sand, - 2-00 



Ash-coloured clay, - - 8*00 



10000 



20* 



