'91I.I STEVEXSOX— FORMATION OF COAL BEDS. 593 



conceives that the Everglades of southern Florida, with an area of 

 about 7,000 square miles, owe their origin to outward advance of 

 mangroves on shallows of the coast. 



The freshwater swamps of the Atlantic and Gulf coasts are, for 

 the most part, sharply distinct from the tidal marshes, even where 

 the latter have encroached. Cook^''" has shown the relation in X"ew 

 Jersey by a section extending from Dennisville to Delaware bay, a 

 distance of about one mile. The cedar^"' swamp begins at the edge 

 of the low upland and gradually deepens to 15 feet. Like most of 

 the cedar swamps in Xew Jersey, it has been cleared, but clusters 

 of young trees up to 100 years old remain here and there on the 

 surface, which is only a few feet above high tide. The cedar grows 

 densely but slowly. Old stumps show more than 1,000 annual rings, 

 but those near the bark are as thin as paper and the stumps rarely 

 exceed 3 feet diameter, though some have been seen which were 7 

 feet. The swamp soil is black, peaty, 13 feet thick at Dennisville 

 and, when dr}'. burns. It shows no admixture of foreign material 

 and contains only 3.35 per cent, of ash, the water in the dried peat 

 being from 12 to 16 per cent. It is very loose and porous, always 

 full of water; the roots of the trees run through it in every direc- 

 tion near the surface, but do not penetrate to the solid ground. 

 Where the peat cover is thin, the roots do pass through to the under- 

 lying soil, but, in that case, the wood is inferior and it cannot be 

 utilized in manufactures. 



Trunks of trees are buried at all depths and are so numerous that 

 one has difficulty in thrusting a sounding rod to the bottom. Some 

 had been blown over when rotten ; others were merely uprooted. 

 Some, blown down, lived for a considerable time afterward. The 

 prostrated trunks lie in all directions and the conditions are precisely 

 the same as those now seen on the surface of the swamp. Large 

 stumps have been found, which grew over logs, now enveloped by 



'"" G. H. Cook, op. at., pp. 301. 302, 355, 356, 360, 361, 484. 



'"^ The cypress or white cedar of X^ew Jersey is Chamacyparis thyoidcs, 

 which is found in swamps from Xew Hampshire to Florida and westward 

 to the Mississippi. The bald cypress is Taxodhim distichuin, a form surviv- 

 ing from the middle Tertiary, which extends from southern Delaware along 

 tlie coast to Texas and up the Mississippi to southern Illinois. 



191 



