PALiEONTOLOGICAL REPORT OF GEOLOGICAL SURVEY. 517 



human life is limited to a day, in comparison with the innumerable 

 ages of our world, we can sometimes observe those changes, and even 

 analyze their causes. In the peat bogs of some high valleys of Switz- 

 erland, the bottom of the marshes is strewn with large trunks of oaks, 

 and there the climate is so cold now, that the pines alone can grow. 

 In Denmark this change of vegetation is also remarkably observed in 

 deep bogs, which the proprietors find profitable to dry with hydraulic 

 machines for the timber which they exhume. One of the most remark- 

 of them has been explored and described, more than ten years ago, by 

 the writer of this report* as its bottom, over the fire-clay, was first 

 found four or five feet of very black peat, overlaid by a forest of pines, 

 lying in the direction of the dip of the basin, viz : their roots against 

 the sides. The diameter of many of their trunks was about one foot. 

 Over the pines a bed of black peat, five to six feet thick, was still cov- 

 ered by an overthrown forest of white birch trees. A new bed of peat, 

 six to eight feet thick, had buried it under its formation, and was over- 

 laid by a third forest of oaks, of which the trunks, three to four feet 

 in diameter, were so well preserved that they were sawed on the place 

 and used for timber. Over this lay five to six feet more of peatj and 

 the whole deposite was covered with humus, and a living forest of 

 beach trees. The whole formation measured about thirty feet. 



Along the shores of the Ohio and Mississippi river there has been 

 deposited here and there, in different places, a quaternary formation re- 

 markable for its thickness. Near Columbus, Kentucky, it elevates its 

 white banks 160 feet above the level of the Mississippi river. | In its 

 upper bed — a fine silicious loam — there is an abundance of shells, 

 which, except one species, are still found living in the river below. 

 This single species, either entirely disappeared or transported to some 

 distant region, is sufficient to prove that if a new bed of loam was de- 

 posited now above the one mentioned, a close observer would already 

 find a difference in their fossils. The lower bed of this quaternary de- 

 posit contains a quantity of leaves, already carbonized, the outlines of 

 which are perfectly well preserved in the hardened white clay. Among 

 them, the predominant species is an oak, (quercus virens), which, in 

 our times, has its peculiar station along the shores of the ocean, and 



•Explorations in the north of Europe, for the study of the coal formations. (Neuchatel, 

 1846.) 

 t First report on the Geological Survey of Kentucky. 



