THE HAGERSTOWN LOAM. 5 



limestone soils of the Clarksville series, which are upland soils. The 

 soils of the latter series are usually to be distinguished from those 

 of the Hagerstown series by the gray color of the surface soil and 

 by the presence of small or large quantities of chert and flint in both 

 surface soil and subsoil. 



SURFACE FEATURES AND DRAINAGE. 



While the Hagerstown loam always occupies valley positions 

 with respect to other upland soils, its surface is by no means level. 

 In each particular area where it occurs, whether the soil be developed 

 in belts several miles broad and many miles long, or as small narrow 

 stretches, where the limestone still persists between bordering areas 

 of more resistant rocks, it has been weathered away by the solution 

 and removal of a large proportion of the calcium carbonate, or lime. 

 Irregularities in the rate of this solution, due to differences in the per- 

 meability or the hardness of the parent rock and to other causes, 

 have in all cases led to the development of a gently rolling to undu- 

 lating surface valley floor, and low ridges and rounded hills are sepa- 

 rated by minor valleys, small depressions, and the pitted, sink-hole 

 topography which is characteristic of the regions underlain by pure 

 limestones. 



Owing to the fact that this soil type is distributed through a long 

 major valley and through a multitude of smaller separate valleys, 

 as well as to its geographical occurrence over a considerable range of 

 ' territory, the absolute elevation of the surface of the type above sea 

 level varies considerably. In general, however, the greater part of the 

 area of the Hagerstown loam is found at an altitude ranging from 

 about 250 feet to approximately 1,000 feet above sea level. Certain 

 separated valleys, however, are found at altitudes as high as 2,000 

 feet. The minor irregularities of elevation within the different areas 

 of the type are usually included within a range of 200 feet, although 

 this is sometimes exceeded, particularly in the more southern areas. 



In addition to the major streams which flow through and across 

 these limestone areas and furnish an adequate surface drainage to the 

 type, there is also hi many of the areas an intricate underground 

 drainage through caverns in the limestone rock. The surface waters 

 flow across the soil for short distances and sink through round and 

 kettle-shaped depressions into the crevices and caves hollowed 

 within the underlying limestone. In this manner the drainage is 

 carried off by underground streams and rivers which reappear in 

 many instances at distant points in the form of great " boiling springs." 

 This underground drainage in addition to the surface drainage is 

 characteristic of the areas covered by soils of limestone derivation 

 and particularly of the soils of the Hagerstown series. 



