78 GEOLOGY OF THE KARRAGANSETT BASIK 



nature, responding at once to manuring. Moreover, they are readily, 

 though temporarily, much improved by plowing in green crops, the store 

 of vegetable matter thus introduced into the earth serving to promote the 

 solution of the feldspar, mica, etc., which exist in the mass, though the quan- 

 tity is not considerable. These sand-plain soils, because of the absence of 

 bowlders, are easily tilled; they can at certain points be readily irrigated; 

 and they thus are likely in the modern time of intensive agriculture to be 

 valued more highly than heretofore. 



The inundated lands of this district include a small area of marine 

 marshes and a considerable extent of fresh-water swamps. On account of 

 the limited range of the tides along this part of the coast, the reclamation 

 of the marshes can not be easily effected by diking. These areas will 

 therefore not receive further consideration. The fresh-water swamps, 

 including in this group all the lands which are made untillable by tempo- 

 rary flooding in the planting season, occupy an aggregate area of about 

 45 square miles, or nearly 28,000 acres. The larger part of this swamp 

 area is to a greater or less extent used as a source of water supply for 

 mills, the waste of the flood times being there stored for use in droughts. 

 Until this use of the swamps is abandoned it will not be possible to win 

 any large portion of these over-watered soils to agricultural use. About 

 one-third of the total area consists of bogs of limited extent, which do not 

 serve as reservoirs and are therefore open to improvement. In most 

 instances these fields can be readily drained by means of inexpensive 

 ditches. When so unwatered, the areas afford soils of two distinct groups. 

 Around the margins of each area there is normally a belt where the peaty 

 matter has not accumulated to a thickness of more than a foot, and where, 

 after being allowed to dry, and consequently to shrink, it can, by deep 

 plowing, be incorporated into the soil. In these portions of the drained 

 swamps tillable fields of very superior quality may be obtained. Within 

 the area of the basin there is probably a total extent of not less than 6,000 

 acres that is thus available for agriculture. Such ground is remarkably 

 well adapted to market gardening. When the peat of a drained bog much 

 exceeds a foot in thickness, it is difficult to reduce the area to ordinary tillage. 

 The only effective way of accomplishing this result is by securing condi- 

 tions of exceeding dryness by extensive ditchings, after which the peat may 

 be burned, as is done in northern Europe. In the present condition of our 



