POSTGLACIAL, &*., DEPOSITS OF CONTINENT. 483 



remains might throw light upon the question of postglacial 

 climate in the inland districts of our continent. In those regions 

 all the relics we are in search of must he looked for in fresh- 

 water tufas, river- and lake-alluvia, and peat-bogs ; and these 

 last accumulations, as I have indicated, are by much the most 

 important. They attain a great development in Holland, Den- 

 mark, Schleswig-Holstein, and Northern Germany, where, owing 

 to the absence of coal, they are of the greatest value, and were 

 even more so before the introduction of railways rendered the 

 mineral fuels of other countries more available. Accordingly, 

 we find that the peat has been carefully studied from early times 

 by Scandinavian, Dutch, and German writers, so that the litera- 

 ture of the subject is voluminous. The older descriptive 

 accounts, however, are taken up principally with the economic 

 importance of the subject, with the extent of the bogs and the 

 quantity available for fuel, with the chemical composition and 

 relative quality of the different kinds of peat-earth and turf. 

 There are few of those writers, however, who quite ignore the 

 geological aspect of the question ; and some of them, especially 

 Degner, have discussed the origin of the peat and the buried 

 trees which it so frequently encloses with great acumen and 

 intelligence. But it is to the more recent essays of Steenstrup, 

 Grisebach, Nathorst, Blytt, and others, that we are indebted for 

 an account of those facts which point to former changes of 

 climate. The earlier observers have generally attributed the 

 formation of the bogs to the felling of the ancient forests by the 

 Eomans, but later investigations have shown that most of the 

 bogs date back to a far higher antiquity, and owe their origin to 

 the operation of natural causes. It is not my intention, however, 

 to give a general account of the peat-bogs of Northern Europe, 

 which would lead me far beyond the limits of the present 

 inquiry, and I .must therefore content myself by referring the 

 reader to the various treatises mentioned in the note below. 1 



1 Among the better known and more interesting treatises are the following : — 

 Abildgaard : Abhandlung vom Torf, 1766 (translated from the Danish of 1762). 

 Blytt : Essay on tlie Immigration of the Norwegian Flora during alternating Rainy 

 and Dry Periods, 1876, p. 37. 



