94 ECONOMICAL GEOLOGY. 



benefit them ; but a light coat of lime or ashes will usually 

 be sufficient to make them produce clover and fresh 

 grasses, or to fit them for tillage. 



There is a large area of salt-marsh which is now en- 

 tirely unimproved, and at the present price of lands, it 

 would not pay interest on costly improvements; but a 

 moderate expense, by which it could be made to produce 

 saltrgrass suitable for mowing, would be found profitable. 

 Salt-hay is in demand in the cities and towns for litter 

 and for packing merchandise ; and at fair prices, the sup- 

 ply is not sufficient to meet it. By proper ditching, open- 

 ing the salt-holes to the flow of the tide, and other compa- 

 ratively cheap improvements, a growth of grass might be 

 produced. Farther up the bay, it has become a regular 

 business to cut salt-hay for the city markets. With the 

 new adaptation of horse-power to cutting this kind of 

 grass, a great facility is added for turning to profit this 

 hitherto waste land.* 



* The mud which is brought on the marshes is of much the same character with that 

 deposited on a tract of land at the mouth of tho river Humber, on the east coast of Eng- 

 land. The mud is there called marp, and the process of filling up low grounds with it, 

 is called warpiiu/. "About 20,000 acres of fine, productive soil, averaging at least two 

 feet in thickness, have been thus made by artificial deposition, covering up poor, worth- 

 less wastes, and giving a more elevated surface for securing good drainage. Five or six 

 hundred acres have been sometimes warped in one piece ; but the compartment, as it is 

 called, which is banked round and laid open to tho river water, is generally of much 

 smaller extent, say fifty acres or less, being such a portion as the farmer can conveniently 

 spare at a time. 



" The thickness of the warp deposit varies from one to three feet, the land being raised 

 to this extent in one, two, or two and a half years. Sometimes the spongy moor subsides 

 80 much with the weight of solid material thus laid upon it, as to need a second warping 

 lifter a few years; but once is generally suflScient. 



"A sluice having been erected in the bank of the river, and a main drain cut from it 

 to the land which is to be warped, (this drain being suffloienUy large, say of three times 



