144 THE SOILS OF CALVERT COUNTY 



in water. Such a course gives rise to continuous, homogeneous layers 

 of clay, while the Leonardtown loam— where undisturbed by cultivation 

 and by the action of frost, rain, and other atmospheric agencies — 

 presents the appearance of an accumulation of clay lenses or nodules, 

 imperfectly separated from each other by veins and pockets of sand 

 interspersed with scattered pebbles. 



A visit to the present cliff line of Chesapeake Bay in Calvert County 

 will give some idea of the manner in which the clay lenses of the 

 Leonardtown loam were formed. Wherever the waves are at present 

 cutting on clay layers steep cliffs are formed, and the continual wearing 

 near tide level undermines large masses of clay which fall down within 

 reach of the waves, where they are further broken up into boulders and 

 pebbles or ultimately reduced to a fine mud. The mud is generally 

 washed away to some distance and only settles to the bottom in com- 

 paratively still water, while the pebbles and boulders of clay are rolled 

 on the bottom of the bay through accumulations of sand and mud and 

 finally come to rest, unless completely broken up, as a pavement of 

 clay lumps interspersed with finer materials. The waters of Chesa- 

 peake Bay are so shallow at present that only small portions of its 

 bottom lie below the zone of wave action, especially during the more 

 severe storms. As a result the clays are usually broken up very 

 completely and only the finer sediments are deposited. Still enough 

 of the boulders and pebbles survive, even along the shore, to give an 

 idea of the general operation of wave forces and of the deposition 

 resulting from such action. If the waters of the bay were deeper, 

 tlie shoreward slopes more shelving, and the materials worked upon 

 more resistant to wave action, it is easy to see that the result would be 

 a quite general deposition of beds of clay pebbles. 



The Leonardtown loam, over a large part of the area occupied by it, 

 was deposited in just such a manner. The subsoil of this formation 

 is mottled red, yellow, purple, and gray by the deposition of hydrated 

 iron oxide in various proportions in irregular patterns. A close ex- 

 amination of this mottling shows that the darker colors outline a series 

 of clay lenses, lying with their shorter axes nearly vertical, and with 



