PALjEONTOLOGICAL report of geological survey. 507 



The fucoides, or marine weeds, are of this kind. To elaborate wood, 

 the plant wants the contact of the air with the porous surface of its 

 leaves. The marsh plants, then, having their roots fixed in the ground 

 below water, expand their leaves either on the surface of the water or 

 above it. Trees need, for their vegetation, the absorption of air 

 through their roots. Hence, those which grow on the bogs, extend 

 their roots and rootlets in a large circuit, let them run near the surface 

 among the mosses, and ordinarily plant themselves on a higher level, 

 either on the decayed trunks of other trees, or on some heap of mat- 

 ter. In any case, a formation of peat is impossible in a marine basin 

 not entirely secured against the action of the tides, or in the marshes 

 of rivers, which, though covered with high water in the spring, become 

 dried by the heat of the summer months. Along the shores of the 

 ocean, of our lakes or our large rivers, there are extensive marshes, 

 inaccessible during the spring, and even during part of the summer, 

 covered with rushes and reeds, the bottom of which is constantly and 

 slowly elevated by thin layers of mud or clay, but never covered with 

 peat. 



The same phenomenon is produced in lakes and bayous, where water 

 is too high for the growth of the plants, and on the borders of which 

 the water level is not constant. The matter deposited at the bottom 

 of those deep marshes is constantly a fine mud. 



There is perhaps no place in the world where the process of the for- 

 mation of coal may be studied, with better chances of a clear elucida- 

 tion of all its phenomena, than in the Dismal and Alligator swamps 

 of southern Virginia and North Carolina. The extent, though truly 

 nothing compared with the area of the coal-fields of America, covers, 

 nevertheless, thousands of square miles. They are separated from the 

 bays and sounds that surrounds them by broad hills, and large banks 

 of sand, bordering the Atlantic, in a continuous row, from Cape 

 Henry, or Norfolk in Virginia, to the mouth of Cape Fear river, or 

 Wilmington in North Carolina. They contain, in their wide area, sand 

 hills, deep deposits of peat, and lakes. The hills are covered with the 

 vegetation of dry land. The peat, from one to fifteen feet thick, 

 follows at its bottom the irregularities of the surface on which it rests, 

 thinning and disappearing entirely where it abuts against the hills : 

 for a bed of peat, depending for its formation on the level of the water, 



