262 GREEN SAND AND CRETACEOUS. 



ter, appear at Ash wood and Wilmington, on tt\e 

 Cape Fear River, in North Carolina ; and in Sou*h 

 Carolina they are again seen on Lynch's Creek, 

 and on the Pedee and Santee Rivers, as well as in 

 the region west of the city of Charleston. Farther 

 south, they occur in Sandersville, in Georgia ; and 

 they occupy a large extent of country in Alabama. 

 The same strata cover nearly the whole state of 

 Mississippi, and also abound in the southwestern 

 portion of Tennessee, Louisiana, between the Alex- 

 andria and Natchitoches, and on the Washita Riv- 

 er, and in Arkansas on the calcareous platforms of 

 Red River. But, though these cretaceous forma- 

 tions belong to the same period, yet the northern 

 and southern sections present very marked differ- 

 ences of mineral and fossil constituents. The 

 northern, or green sand formation, may be said 

 to extend through New-Jersey and Delaware, to 

 the eastern shore of Maryland, over a nearly hor- 

 izontal plain, the mean elevation of which above 

 the sea is not more than from 40 to 60 feet, 

 though in the northeast of Monmouth it rises 300 

 feet above the sea. It consists of strata of a 

 friable material, more or less arenaceous or ar- 

 gillaceous in its texture, of a dark greenish or blu- 

 ish colour, including bands or layers rich in a pe- 

 culiar fossil, and characterized by a thick bed of 

 green sand, or, as the inhabitants term it, marl. 

 The northern and western portions of the newer 

 secondary or cretaceous formations consist of lime- 

 stone of various degrees of hardness, more or less 

 abundant in fossils, and having the particles of 

 green sand only sparsely disseminated through the 

 mass. These limestone strata, which thus compose 

 nearly the whole of the cretaceous group in the 

 Southern States, exist on a scale of vast extent and 

 thickness, rising into bold, undulating hills, resem- 

 bling the surface of the chalk in Europe. 



The 44 marl" or green sand stratum contains, often 

 as its sole ingredient, a peculiar mineral, in the 



