80 



NORTH-CAROLINA Q-EOLOGICAL SURVEY. 



to ascertain the amount which may be profitably employed 

 and how far they may be transported has to be ascertained 

 by analysis. 



There are several localities at which the green sand occurs. 

 The strongest marl beds occnr at Black Rock on the Cape 

 Fear river, about twenty-five miles above Wilmington. It 

 forms low bluffs at several other points, but it appears to 

 terminate from two to five miles below Brown s landing. 



Striking across the county to the eastward it again appears 

 prominently .at Rocky Point, twenty miles above Wilmington. 

 The green sand, unlike the shell marl, forms continuous beds, 

 but as its beds are undulating, they rise at certain points to 

 the surface, and then sink beneath it. 



In this State I have been unable to determine its thickness, 

 or the number of beds which properly belong to it. For this 

 reason I propose to describe them now, as they are known to 

 exist in New Jersey, inasmuch as such a description may aid 

 others where it exists, to determine with accuracy both their 

 thickness and the number of beds which compose the green 

 sand formation in North-Carolina. The difficulty in the way 

 of solving this question is the slight elevation of the banks 

 of rivers and ravines above the adjacent country. We find 

 at Black Rock, for example, a strong bluff of this deposit, 

 but the water is never low enough to disclose the bottom 

 beds, or the masses upon which it rests. 



In order to state all that is known of the green sand and 

 marl, and their relations to each other, I have prepared sev 

 eral sections which show how they are situated with respect 

 to each other. From these sections it will be seen that the 

 marl beds vary much in thickness, and in their relations at 

 different places where they are exposed to the best advant 

 age. Thus, section I, fig. 1, exhibits all the beds as they exist 

 at Black Rock: 



