MARL. GREEN SAND. 



343 



itself to the philanthropic of all our large cities, 

 viz., the introduction of peat as a fuel to supply the 

 necessities of the poor. It is believed that much 

 suffering may be prevented and much comfort pro- 

 moted, by the use of peat in all places where fuel 

 is expensive, as in New-York and Albany." 



Marl. — There are two substances which go un- 

 der the name of marl in this country, viz. : 1. The 

 Calcareous Marl, composed chiefly of carbonate of 

 lime. 2. The Green Sand Marl, which we have de- 

 scribed in a former chapter. 



The first kind of marl may be either a friable 

 mixture of lime and clay, or partially decomposed 

 beds of shells. In the New-England States, espe- 

 cially in the western part of Massachusetts, this 

 marl often occurs in beds of from two to twelve 

 feet thick, generally in marshes or on the borders 

 of ponds. It seems to result from the carbonate of 

 lime brought into ponds by water, and there depos- 

 ited. After a while perhaps the pond fills up, ve- 

 getables begin to grow over the marl, and thus at 

 length a deposite of peaty matter covers the marl. 

 When dry, this substance is nearly as white as 

 chalk, and much lighter than common soil ; when 

 wet. it is of a light gray colour, especially if it con- 

 tains much organic and earthy matter ; the quantity 

 of lime it contains may generally be told by its de- 

 gree of whiteness. Prof. Hitchcock states that 

 this marl is found almost exclusively in swampy 

 ground, generally quite wet swamps, and always 

 covered by a stratum, often several feet thick, of 

 black vegetable matter approaching to peat. Hence, 

 as these swamps are not easily excavated, the marl 

 is not apt to be discovered. Prof. H. recommends 

 passing down an iron rod several feet long, with a 

 groove in the end like an auger, in order to discover 

 marl in places where it is suspected ; or even a 

 rough pole, which he says answers the purpose just 

 as well, some of the substance always adhering to 



