4 SOILS OF THE EASTERN UNITED STATES. 



downward into a yellow heavy loam or clay loam subsoil, which in 

 turn grades into a heavier clay loam or clay subsoil at a depth of 2 

 feet to 1\ feet. This deeper subsoil is not infrequently of a brown or 

 reddish color and in practically all cases it is sharply bounded by the 

 underlying undissolved limestone rock. It is a general characteristic 

 of the type, as with other soils derived from the harder limestones, 

 that there is no gradation from subsoil into rock, but the subsoil 

 material rests upon an uneven and corroded rock floor. This arises 

 from the natural processes by which the soil is formed. It has been 

 produced by the partial or complete solution of the calcium carbonate 

 of the parent rock. The actual soil and subsoil material consists of 

 the less soluble residues which have accumulated over the rock itself. 

 There is thus no transition from rock to soil, as in case of soils derived 

 from granite or sandstone, but a sharp boundary instead. 



Only where thin layers of sandy rock exist, or where there has been 

 an unusual amount of siliceous material in the limestone, are there to 

 be found stony or rocky areas within the region occupied by the 

 Hagerstown loam. The pure limestone which gives rise to the typical 

 areas does not contain a sufficient amount of the less soluble materials 

 to leave either stone or chert fragments in the soil or subsoil of this 

 type. 



It is not infrequently the case, even in the most t} T pical areas of the 

 Hagerstown loam, that uneven hardness in the rock or irregular solu- 

 tion, due to other causes, leaves ledges of the parent limestone which 

 protrude through the soil covering. These limestone ledges exist 

 even in the best fields in practically all the areas where the type has 

 been mapped. They are not entirely undesirable, since in many 

 localities they furnish a supply of limestone to be burned in kilns 

 upon the farm. The resulting stone lime is liberally applied to the 

 soil in all of the more northern communities, where this practice pre- 

 vails. These ledges also furnish building stone and material for the 

 construction of highways and give a considerable revenue in those 

 localities where they are thus utilized. The limestone ledges where 

 they are unduly numerous are to be avoided, especially for the pur- 

 poses of orchard planting, since the shallow covering of soil along their 

 flanks does not maintain a sufficient amount of moisture to satisfy 

 the needs of plants which are to occupy the ground for such a long 

 period of time as do fruit trees. 



The Hagerstown loam is easily distinguished from the majority of 

 other soil types occurring within the same region. It is preeminently 

 "the limestone soil" as distinguished from soils derived from other 

 classes of rock. The surface soil is brown, friable, and soft and 

 easily distinguished from the Hagerstown clay, which is much stiver 

 and more tenacious. The soils of the Hagerstown series appear in 

 various positions, but always at relatively lower elevations than the 



