GEOLOGICAL SURVEY OF THE TERRITORIES. 353 



This much for mere surface appearances. The diversity becomes, 

 however, far greater in penetrating nearer to the shore of the ocean, in 

 those dismal swamps of the south where it is caused, not merely by the 

 variety of the vegetation, but by modifications of level from the inces- 

 sant action of the water, either in seeking an outlet, or by alternately 

 invading low land or heaping upon it materials which raise it above 

 the sea. Isolated lakes, like the Drummond Lakes, for example, 

 are met with, which formerly were covered by forests, now sunk 

 to the bottom, where, near the borders, the tops of trees, (bald cypress,) 

 still standing, appear above the surface of the water, their trunks im- 

 mersed 10 to 15 feet deep. A bed of mud is slowly deposited over this 

 sunk forest, from particles of matter brought by water, while on the 

 borders the floating vegetation of the peat, the Bphagnum,* especially, 

 already begins preparing for the future a new bed of materials, which 

 may be extended over the whole surface of the lake. Suppose a de- 

 pression of this floating mass, and the bottom of the lake is then over- 

 laid by two beds of combustible matter, separated by a bed of mud, 

 "while, on the borders, the peat of an uninterrupted growth has, of 

 course, formed a single bed. This represents, if time enough is admit- ' 

 ted, a bed of coal, compact or in one at some places, separated in two 

 or more beds at some others. This division of the peat-beds by foreign 

 matter, either deposited or brought up by the same agency, is remarked 

 everywhere and often continuous and increasing in the same direction. 

 Some of the lakes of Switzerland are separated by peat-bogs of great 

 extent, some of them more than fifty square miles in area. In the mid- 

 dle of the greatest of these bogs the bed of peat is, on the eastern side, 

 8 to 10 feet thick, without parting, but toward the west it is horizontally 

 divided in the middle by a streak of sand, which, for six miles farther, 

 increases by degrees to 3 feet. In coming to the borders of the lake 

 the lower bed of peat passes under the sandy bottom. In Holland, 

 borings for water record one bed of peat farthest from the shores in 

 coming nearer to them, proportionally to distance, two, three beds, or 

 more, formed by superposition of sand and mud, causing temporary or 

 permanent divisions of the original bed. 



The same modifications are observable in the peat-deposits of this 

 time, and their cause plainly exposed to the explorer in the swamps of 

 this country nearer to the shores of the ocean. Here estuaries indent- 

 ing the laud form a true net-work of canals, lagoons, bayous, cut by 

 narrow capes, islands of various size, some of them a mere mass of 

 heaped vegetables, floating here and there. The lowlands are mostly 

 overgrown with a luxuriant vegetation, aftording materials for the growth 

 of the peat : but in some localities these swamps are slowly invaded again 

 by the sea, which has cut a channel through the beach somewhere 

 near by and brings sand over them. By and by these peat-deposits 

 will be buried apparently forever. But if a current or a storm, or 

 some other casualty, closes the channel, the lagoon, protected against 

 marine influence, becomes an inland lake with a permanent level, 

 has its brine slowly changed into fresh water by the ingress of some 

 river, and after a while the same kind of vegetation will re-appear 

 over the lagoon and begin its productive work anew. There is 

 along these low shores a perpetual contest for predominance between 



* ^iifiCi(iHoi Sphagnum, when growing in water, extend their filaments over the surface 

 in contiiiuons and innumerable ramifications, which soon form a net of floating vege- 

 tation, where other plants by and by take root and live. On a solid ground the same 

 species grow in compact mass, all their stems erect, closely pressed together. 



23 G s 



