124 ECONOMICAL GEOLOGY. 



greater even than what is due to the fertilizing substances 

 it contains ; acting by the clay it contains to make them 

 withstand drought better, to be more retentive of manures, 

 and to favor the growth of wheat and grass. 



Shell-marl and Shells. — There are no extensive deposits 

 of shell-marl in the county; one small one has been men- 

 tioned on p. 27, as occurring below Beesley's Point. This 

 consists of 41 per cent, of crumbled shells, probably of the 

 oyster, and the remaining 59 per cent., of a bluish mud, 

 like that of the present oyster beds. It is probable that 

 as the county is more cleared up, other deposits of this 

 kind will be found. Tor applying to the soil, it only needs 

 exposure to the weather long enough to slake fine, when 

 it can be spread upon the surface. Both the lime and the 

 mud are valuable fertilizers. 



The deposits of recent shells of the clam and oyster, are 

 very common, and in some places, very large. At Beesley's 

 Point, I saw a large pile of broken clam shells ; no others 

 were mixed with them, and there were no whole shells ; 

 the . fragments were quite small.* They are just in the 

 borders of the marsh. A number of other piles of shells, 

 of the same kind, are known along the shore. Large piles 

 of oyster shells are found in different places along the 

 borders of the creeks and the upland. Oyster shells are 

 also found in great quantities in the bottoms of some of 

 the creeks and bays. They also form solid beds of con- 

 siderable thickness and extent in Delaware Bay, opposite 

 the mouths of Dennis and other creeks which run into 



* They are supposed to be the remains of olam shells, broken up by the Indians, in mak- 

 Ing wampum. 



