PALS10NT0LOGICAL REPORT OP GEOLOGICAL SURVEY. 505 



showing where then were the first shores of the ocean — the first out- 

 line of the Alleghany mountains perhaps. 



The conglomerates of the anthracite basins of Pennsylvania are 

 about fifteen hundred feet high, composed of sand and pebbles of 

 quartz, which are sometimes as large as hens' eggs. On the contrary* 

 in the western part of the Coal Measures, in Indiana, Kentucky, and 

 Tennessee, they are comparatively thin, and of a finer texture — just as 

 it happens that near the shallow shores of our lakes, or of the Atlantic, 

 the gravel and coarse materials of the bottom are heaped by the waves 

 nearer to the margin, in proportion to their size, the finest particles of 

 sand being necessarily drawn farther from the shores where the action 

 of the waves is less violent. It was in this manner that the first basin 

 of the coal was prepared. Bordered to the east by a chain of hills, the 

 bottom was slowly upheaved, and the ocean darned far away to the 

 west, began there, by its perpetual movements, to build again its new 

 shores, and to close in the coal basin with high banks of sand and grav- 

 el. This separation was necessary, for a shallow, quiet, water, of a 

 constant level, is the first condition of the formation of peat, and con- 

 sequently of coal. 



The plants of the bogs have a peculiar growth and a peculiar com- 

 position. They live ordinarily half immersed in water, and raise their 

 stems, branches, leaves, and flowers above the surface. They are gen- 

 erally of a woody texture. Even the mosses and the grasses of a 

 peat-bog contain, comparatively to their size, as much woody fibre as 

 the hardest oak. The trees are most of them resinous. In the north- 

 ern part of the United States the balsam-fir, the black and white 

 spruce, the tamarack, the arbor- vitse and the white cedar; in the south, 

 the bald cypress, the great and small laurel magnolias, the tulip-tree, 

 are commonly seen growing on the cedar swamps, with birches, alders, 

 poplars, and other resinous shrubs. The peat bogs of Europe are 

 abundantly covered with a kind of dwarf-pine, from the leaves and 

 twigs of which the rpsin trickles upon the mossy ground, forming all 

 around the trees a hard floor of tar many inches in thickness. Most 

 of the plants of those marshes, except a few trees, belong to that pe- 

 culiar station; they do not grow out of their bogs, neither can they 

 be transported and cultivated out of them. For that reason the vege- 

 tation of the cedar swamps cannot be taken as a true representative of 



8* 



