594 STEVENSON— FORMATION OF COAL BEDS. [November j, 



their roots, and at the bottom are found worthless logs of cedar 

 belonging to trees which were rooted in the solid ground below. 



Shaler^'"* has given a general description of the Dismal Swamp, 

 an area of about 500 square miles, at only a few feet above tide 

 level. It was much larger, but a great part has been reclaimed by 

 draining. The peaty deposit rests on Pliocene sands, of which 10 

 to 14 feet are exposed on the border ; but this is not wholly certain 

 as the bottom has been reached at only one place within the swamp. 

 C. A. Davis has stated recently that the peat is at least 15 feet thick 

 and of good quality. On the western border is Drummond lake, 

 6 feet deep and somewhat more than 2 miles wide. Shaler says 

 that, here and there within the swamp, one comes to drained areas 

 of considerable size, one of which, embracing about 2 square miles, 

 has long yielded fine crops of maize. He notes that Sphagnum has 

 a very small place in this swamp and that it is an unimportant factor 

 everywhere south from the Potomac and Ohio rivers, where the 

 greater heat and decreased rainfall prevent its luxuriant growth. 

 The most important peat-making plants in the region south from 

 those rivers are canes, a grape, the bald cypress and the juniper with, 

 in some localities, the dwarf palmetto — among these, he assigns the 

 chief place to the common cane. 



The greater part of the Dismal Swamp is under water during 

 most of the time, but there are elevations rising not more than 3 

 feet above the general level ; yet the drainage due to this slight ele- 

 vation suffices for growth of pines belonging to the common southern 

 species. In the main area, water-covered, one finds three trees, Ta.vo- 

 diiDii disiichnm, the bald cypress; Junipcrus virginiana, the juni- 

 per; and Nyssa syk'atica^the black gum. The juniper occupies spots 

 usually somewhat desiccated during the dry season, but the others, 

 being provided with special appliances, live where their roots are 

 covered with water during even the growing season. The forest is 

 very dense and passage through it is rendered difficult by projecting 

 knees of cypress and the arched roots of Nyssa, while everywhere 

 is a profusion of other plants. The surface is covered with a litter 



'»■■' X. S. Shaler, Tenth Ann. Rep. U. S. Geol. Survey, pp. 293, 313, 321, 

 PI. K, <), 10, V\g. 29. 



192 



