338 AXXL'AL OF SCIENTIFIC DISCOVERY. 



remains of very different dates, made by some such process as that 

 indiVafc'l iu speaking of the first division, might subsequently have been 



Such arc the reasons on which Dr. Anderson bases his conclusion, that 

 there is nothing in recent geological discoveries to warrant a departure from 

 the usually accepted date of man's recent introduction upon the earth. 



ARE THE COAL-MEASURES A SINGLE, UNIQUE FORMATION? 



Are the coal-measures a single, unique formation? Do they belong to a 

 single epoch, or are they composed of a succession of formations, separated 

 by immense spaces of time, and of which the different stages might be com- 

 pared to those of the recent formations : the Eocene, the Miocene, and the 

 Pliocene, for example? In the last case, can we admit the vegetation of 

 which the remains have been preserved in the shales of the coal, or the vege- 

 tation of the coal-marshes, as a true representative of the flora of the various 

 epochs where the coal was formed? Or was it then, as the bog-vegetation is 

 in our time, composed of a peculiar group of plants, adapted to the forma- 

 tion of the coal, pertaining to the marshes only, while another flora, of a 

 different character, was covering the dry land, if there was any dry land, at 

 the carboniferous epoch? 



From the thickness of some beds of coal, representing a mass of combus- 

 tible matter as great at least as that which is contained in our oldest and 

 deepest peat-bogs, from the thickness and various composition of the strata 

 which separate the beds of coal, and from the successive changes in the 

 vegetation of the coal, it appears that the last alternative is admissible. 

 Different hypotheses have been put forward to explain the so-called huge or 

 gigantic vegetation of the coal formations. But there is nothing in the car- 

 boniferous epoch authorizing the suppostion that the power of vegetable life 

 was greater than it is at our time. The combustible matter heaped in some 

 of our peat bogs is sometimes sufficiently thick to be equivalent to the coal 

 of a bed of four to five feet. The trees growing in our marshes or on the 

 peat bogs are generally larger than those which have been preserved in the 

 strata of the carboniferous measures. The Dismal Swamp is impenetrable 

 on account of the great compactness of its vegetation. It is not an easy 

 matter either to get across the heaped, half prostrated, or erect and closelj" 

 pressed trees of our cedar-swamps of the North. If such marshes were 

 extended over the greatest part of the United States, they would present a 

 fair representation of those of the carboniferous period. 



The occasional appearance of the petrified trees, standing imbedded in 

 sandstone, does not give evidence of a rapid formation cither of the coal or 

 of the other strata. Local disturbances may throw a few feet of sand upon 

 a marsh, covered with active vegetation, and thus preserve the stumps from 

 decomposition, and by-and-by these may be converted to stone. The bald 

 cypress and other species of trees grow sometimes in the marshes near the 

 sea-shore under ten feet of water. Whole forests of those trees have been 

 imbedded in a standing position in the marshes around New Orleans. Thus 

 I do not find in the geological records of the carboniferous period any indi- 

 cation of a rapid process of formation, either cataclysmic or abnormal, and 

 I readily admit that each bed of coal, with its accompanying strata of fire- 

 clay and shales, has required for its formation a period of time as long as 

 any of our recent geological divisions. 



