SOILS. 263 



The Potomac deposits contain many coarse sandy strata above the 

 basal beds and these almost invariably carry water. The variability of the 

 beds, however, does not permit of the correlation of the water-bearing 

 horizons except in very closely contiguous regions. 



The Eocene beds of Virginia contain some coarse sand strata, which 

 usually carry considerable water in the central part of the Coastal Plain. 

 The flowing wells at Colonial Beach obtain a large supply of fine water 

 from these strata at a depth of 250 feet, while the Eocene beds at Naylor's 

 Wharf furnish an ample supply at depths ranging from 275 to 325 feet. 



The Miocene formations contain many artesian water horizons which 

 produce flowing wells along the larger streams. According to Darton these 

 waters underlie a belt of country about 20 miles in width lying to the east 

 of a line extending from Mathias Point on the Potomac Eiver to Emporia. 

 Miocene waters can also be obtained to the east of this belt, but they are 

 so apt to be heavily charged with salt that it is usually advisable to seek 

 water in deeper strata. 



SOILS. 



In the Coastal Plain of Virginia there is a great variety of soil types, 

 each possessing special adaptability to certain crops. The region is strictly 

 an agricultural one, consequently great interest is attached to the character 

 of the soils. The soils of a region are formed from the surface portions of 

 the underlying geological formations with which is mixed more or less 

 humus from decaying vegetation. For example, the soils formed from the 

 greensands of the Eocene are distinctive and very unlike those formed from 

 the diatomaceous earth beds of the Miocene. On account of the greater 

 or less diversity in the deposits of a single formation it will not everywhere, 

 however, give rise to the same kind of soil. The Calvert formation, for 

 example, embraces all the deposits formed during a certain period of sub- 

 mergence including clays, sands, diatomaceous earth, and shell beds. The 

 soils formed from the deposits of this formation will therefore vary as much 

 as the strata from which they are derived. Furthermore, the same soil 

 types may be produced from geological formations of different age. It is 

 important then to study in great detail the stratigraphy of the various 

 formations, in order fully to interpret the soils. 



The soils of the Coastal Plain are, for the most part, derived from the 

 Lafayette and Columbia formations which appear at the surface over much 

 the larger portion of Tidewater Virginia. The character of these beds, how- 

 ever, is so largely dependent upon the underlying strata that indirectly 



