11 



which a reboisement of the country might arrest, Denmark has suffered 

 often er than once from disastrous encroachments of the ocean; and in 

 other ways extensive lagoons have been formed. Thus Denmark has 

 come to supply many illustrations of the effects of vegetation, both 

 herbaceous and arborescent, in filling up and drying up marshes in 

 prolonged periods, extending back into pre-historic times. And the 

 Danish language is rich in specific designations given to different 

 kinds or forms of bogs and moors thus formed, whereby the pheno- 

 mena may be more accurately studied. It was in connection with 

 this that my attention was first directed to the physical geography of 

 the country. 



Referring to a work entitled Om MojligJieten och Fordelen af 

 allmanna Uppodlingar i Lappmarken, by L. L. Lsestadius, published 

 in Stockholm 1824, Mr. Marsh remarks, 



" The English nomenclature of this geographical feature does not seem well 

 settled. We have boy, swamp, marsh, morass, moor, fen, turf-moss, peat-moss 

 quagmire, all of which, though sometimes more or less accurately discrimi- 

 nated, are often used interchangeably, or are perhaps employed, each exclu- 

 sively, in a particular district. In Sweden, where, especially in the Lappish 

 provinces, this terraqueous formation is very extensive and important, the 

 names of its different kiuds are specific and exclusive in their application." 



Illustrations are given ; and something similar may be alleged in 

 regard to the nomenclature of these in Denmark. The student of 

 forest science finds the study of the natural history of these bogs thus 

 greatly facilitated. 



In Denmark the tree which most extensively prevails at the present 

 day is the beech. When remains are found at all in a decaying state 

 under the soil, it is in the uppermost layer of peat-bog. As we go 

 further down in the peat, remains of the oak are abundant, though 

 the oak is, in the Denmark of to-day, almost entirely superseded 

 by the beech. At a still lower level we come upon remains of the 

 Scotch fir, and these in great abundance, though this is a tree which 

 has never, within the range of historical times, been indigenous in the 

 country. 



In glancing at phenomena thus referred to, there arises first the 

 question, When did all this take place ? A second question 

 is, Whence came the seeds producing the successive crops of 

 different kinds of trees? And a third is, What light may be thrown 

 upon the physical condition of the country at successive periods by 

 these successive products ? Omitting the discussion of the second of 

 these, so as to gain space, I address myself to the first, and shall 

 briefly advert to the last question ere I close. 



The hunters of the old Danish firwoods, and the fishermen who 

 produced the mounds of shells which are found in Denmark, lived 



