PRIMARY SOILS. 237 



ous matter. The following are the principal varieties of this 

 soil. 



( 1 ) The conglomerate soil, consisting mostly of coarse sand 

 and pebbles which have been once cemented together, but 

 are now crumbled into soil. The rock is known as pudding 

 stone and is found in Roxbury, Dorchester, and many other 

 places in the eastern part of Massachusetts. It is far the 

 best soil found in this class. 



(2) Slati/ soil, of a gray color, more retentive of moisture 

 and often clayey, but capable of being made very fertile. 



(3) Slati/ red soil, in which the rock and the soil is of 

 a deep chocolate ; in other respects it does not differ from 

 the preceding. Sometimes these three kinds are mingled 

 together, and when the coarse pebbles constitute the sub-soil, 

 it is often subject to suffer by drought and to permit the ma- 

 nures to pass through, without producing much effect upon 

 the crop. 



As the coal measures repose upon the graywacke, it of- 

 ten happens that the fine graywacke soil becomes mingled 

 with the carbonaceous clay slate, which renders the soil of a 

 clayey texture. 



4. Claj/ slate soil. This soil is similar to the preceding, 

 but generally finer in texture and more argillaceous or clay- 

 ey. It is the oldest of the secondary soilsj and contains but 

 few remains of plants or animals. The carbonaceous clay 

 slate rocks when mixed with graywacke make a very fertile 

 soil. It is black, retentive of moisture, and well adapted to 

 grain, herdsgrass and clover.* 



V. Primary soils, or soils from the primary stratijied and 

 unstraiijied rocks. This division includes a great variety of 

 soils. The most common variety in New England, are ar- 

 gillaceous slate, limestone, mica slate, talcose slate, gneiss, 

 granite, sienite and porphyry soils. The trappean varieties 

 form a distinct class. 



* See Jackson's Report of Geology of Rhode Island, p. 127. 

 20* 



