COlSrCLTTSIONS OTT ANCIENT CLIMATES. 15 



our own time, is derived from these imperfect details, from the 

 vague statements of ancient historians and geographers in regard 

 to the volume of rivers and the relative extent of forest and cul- 

 tivated land, from the indications furnished by the history of the 

 agriculture and rm*al economy of past generations, and from other 

 almost purely casual sources of information.* 



Among these latter we must rank certain newly laid-open fields 

 of investigation, from which facts bearing on the point now under 

 consideration have been gathered. I allude to the discovery of 

 artificial objects in geological formations older than any hitherto 

 recognized as exhibiting traces of the existence of man ; to the 

 ancient lacustrine habitations of Switzerland and of the terremare 

 of Italy,f containing the implements of the occupants, remains of 

 their food, and other rehcs of human life ; to the curious revelations 

 of the Kjohhenmoddinger, or heaps of kitchen refuse, in Denmark 

 and elsewhere, and of the peat mosses in the same and other northern 

 countries ; to the dwelhngs and other evidences of the industry of 

 Juan in remote ages, sometimes laid bare by the movement of 

 sand dunes on the coasts of France and of the Korth Sea ; and to 

 the facts disclosed on the tide-washed flats of the latter shores by 

 excavations in Halligs, or inliabited mounds, which were probably 

 raised before the era of the Roman Empire.:}: These remains are 

 memorials of races which have left no written records — races 

 which perished at a period beyond the reach of even historical 

 tradition. The plants and animals that furnished the relics found 

 in the deposits were certainly contemporaneous with man ; for 

 they are associated with his works, and have evidently served his 

 uses. In some cases, the animals belonged to species well ascer- 



* The subject of climatic change, with and without reference to human 

 action as a cause, has been much discussed by Moreau de JonnSs, Dureau de la 

 Malle, Arago, Humboldt, Fuster, Gasparin, Becquerel, Schleiden and many- 

 other writers in Europe, and by Noah Webster, Forry, Drake and others in 

 America. Fraas has endeavored to show, by the history of vegetation in 

 Greece, not merely that clearing and cultivation have affected climate, but 

 that change of climate has essentially modified the character of vegetable life. 

 See his Klima und Pflanzenwelt in der Zeit. 



f See two learned articles by Pigorini, in the Nuava Antologia for January 

 and October, 1870. 



X For a very picturesque description of the Halligs, see Pliny, N. H., Book 

 xvi., c. 1. 



