114 BOARD OF AGRICULTURE. 



this lower and comparatively level country, we have various 

 sandy and loamy soils, composed chiefly of the marine deposits 

 of wliich the entire region is made up. Beneath the surface in 

 a large portion of the vast area to which I am referring are to 

 be found those rich resources which under improved forms of 

 human activity and organized industry are destined ere long to 

 transform the wasted fields into a garden of beautiful produc- 

 tiveness. The treasures are the beds of shell marl accumulated 

 in the ancient sea and stored up beneath the soil to serve as a 

 perpetual source of renovation and fertility. 



The tertiary deposits of shells, sometimes of very great thick- 

 ness, showing themselves along the margins of rivers, and in the 

 ravines where they are deep enough, and found in all directions 

 in the interior, furnish to the land large quantities of carbonate 

 of lime ; and associated with this the remains of organic matter, 

 vegetable and animal, deposited at the same time,' materials 

 wliich when dug up and spread over the sands and clays, which 

 are seemingly sterile on the surface, enrich them in many cases 

 to a degree of exuberant fertility. 



Let me now give a little illustration of what may here be seen 

 in reference to the chemistry of the soil. There is one district of 

 the tertiary region, north-east of Fredericksburg, celebrated now 

 in the history of this war, a part of the peninsula called the 

 Northern Neck, between the Potomac and the Rappahannock, — 

 where there are extensive localities destitute of shell marl, 

 altliough it once existed in them in enormous quantity. There, 

 the farmer digging with a view of finding this precious material 

 for manuring his fields, comes upon a mass of clay and sand, 

 sour to the taste and having the smell of sulphur, and which, 

 when applied to the soil under ordinary circumstances, produces 

 a poisonous instead of a beneficial effect. Look at this clay 

 or sand, and you will see that it contains no shells. They could 

 not exist in it, but would be dissolved out and removed by the 

 acid which impregnates the mass. But instead of the shells you 

 will see cavities dispersed in every direction through the clay 

 and sand, which a little observation will show to be what we 

 migbt call the spectres of departed shells. In other words, they 

 are the hollow moulds left by the shells which once abounded 

 in the mass. But what has become of the shells ? Dig down 

 twenty, thirty feet deeper, and you reach a stratum of clay ; 



