203 



near Vincentown. In the bank before us the limestone is rarely 

 more than one foot thick, and reposes upon the greensand, or 

 marl bed, which consists of a series of thin layers of different 

 tints, and various degrees of purity, occupying a depth of at least 

 twenty feet. 



This is a locality containing some very interesting fossils, but 

 the present is not the place to treat of them. The marl has the 

 very usual odour of sulphur, and exhibits, when dry, the gray or 

 white efflorescence. It enjoys a high reputation as a manure. 

 Most of the shells in it show that the carbonate of lime has been 

 nearly all supplanted by oxide of iron, and here, as in the instance 

 of many other greensand marls, the virtues of the mass are not to 

 be attributed to the lime, but to the specific power of the consti- 

 tuents of the dark granules, chiefly the potash. 



Marl from the farm of Fuller Horner, New Egypt. 

 Upper part of the bed. 



Description. — Colour dark olive-green; washed granules very 

 dark green, size large. 



Composition. — In 100 parts : 



Greensand, - - - 100 



Clay, .... none. 



Quartzose sand, - - none. 



100 



The proportion of potash which this marl contains by analysis, 

 is 11 per cent. 



Marl from the bridge at Hornerstown, Monmouth county. 



Description. — Colour, a rather light green. The washed 

 grains quite small, and of a richer green. 

 Composition. — In 100 parts : 



Greensand, ... 75-90 



Clay, .... 2010 



Quartzose, ... 4-00 



10000 



