MARYLAND GEOLOGICAL SURVEY 173 



tions of the area fall within another soil type (Susquehanna clay 

 loam), and these portions are distinguished from the Susquehanna 

 clay by marked features of origin and soil texture. 



Tliat some remedy for the unproductive conditions of the Susque- 

 hanna clay can be devised is firmly believed. The present structure 

 of the soil and subsoil must be changed by the application of sub- 

 stances which will tend to flocculate the soil particles. In this man- 

 ner the circulation of the soil moisture and the soil atmosphere 

 should be facilitated and the stores of plant food, which have been 

 shown by chemical analysis to exist in this soil, should be made 

 available. Lime is one of the substances that produces such a floc- 

 culating effect upon puddled soils, and it not only improves the soil 

 texture, but also aids in the chemical reactions necessary to make 

 available the reserve supplies of plant food. It also acts directly 

 as a plant food itself. Lime has already been nsed upon a soil 

 formed by a surface layer of about 8 inches of Pleistocene loam over- 

 lying the Susquehanna clay subsoil. In this case good clover and fair 

 grain crops have been produced. While the conditions differ from 

 those pertaining to the most marked type of Susquehanna clay, the 

 beneficial results would seem to indicate that the experiment of lim- 

 ing should be thoroughly tried upon that type. The transformation 

 of the semibarren areas of Susquehanna clay to a productive soil is a 

 result greatly to be desired, and thorough experimentation along 

 scientific lines may yet accomplish it. 



The accompanying table shows the texture of typical samples of 

 Susquehanna clay. 



THE SUSQUEHANNA CLAY LOAM. 



Throughout the region occupied by the clays of the Potomac group 

 there are found areas which, owing to the presence of lenses of 

 sand or to the partial covering of Pleistocene material, do not fall 

 within the limits of the Susquehanna clay. These areas, approximat- 

 ing an area of 26 square miles in Prince George's County, are irreg- 

 ularly scattered through the western part of the county. They are 

 foimd on hilltops, on slopes, and in the valleys alike, and are fre- 

 quently cleared, though considerable areas still support a forest 

 growth of oak and pine. 



