iSo CLIMATE AND PRODUCTIONS OP [CHAP. XI. 



These facts are of high geological interest with respect to the climate 

 of the northern hemisphere, at the period when boulders were trans- 

 ported. I will not here detail how simply the theory of Icebergs being 

 charged with fragments of rock, explains the origin and position of the 

 gigantic boulders of eastern Tierra del Fuego, on the high plain of 

 Santa Cruz, and on the island of Chiloe. In Tierra del Fuego, the 

 greater number of boulders lie on the lines of old sea-channels, now 

 converted into dry valleys by the elevation of the land. They are 

 associated with a greet unstratified formation of mud and sand, con- 

 taining rounded and angular fragments of all sizes, which has originated* 

 in the repeated ploughing up of the sea-bottom by the stranding of 

 icebergs, and by the matter transported on them. Few geologists now 

 doubt that those erratic boulders which lie near lofty mountains, have 

 been pushed forward by the glaciers themselves, and that those distant 

 from mountains, and embedded in subaqueous deposits, have been 

 conveyed thither either on icebergs, or frozen in coast-ice. The 

 connection between the transportal of boulders and the presence of ice 

 in some form, is strikingly shown by their geographical distribution 

 over the earth. In South America they are not found further than 48 

 of latitude, measured from the southern pole; in North America it 

 appears that the limit of their transportal to 53^ from the northern 

 pole ; but in Europe to not more than 40 of latitude, measured 

 from the same point. On the other hand, in the intertropical parts 

 of America, Asia, and Africa, they have never been observed: nor 

 at the Cape of Good Hope, nor in Australia.f 



On the Climate and Productions of the Antarctic Islands. Con- 

 sidering the rankness of the vegetation in Tierra del Fuego, and on 

 the coast northward of it, the condition of the islands south and south- 

 west of America is truly surprising. Sandwich Land, in the latitude 

 of the north part of Scotland, was found by Cook, during the hottest 

 month of the year, "covered many fathoms thick with everlasting 

 snow ; " and there seems to be scarcely any vegetation. Georgia, an 

 island ninety-six miles long and ten broad, in the latitude of Yorkshire, "in 

 the very height of summer, is in a manner wholly covered with frozen 

 snow." It can boast only of moss, some tufts of grass, and wild burnet : 

 it has only one land-bird (Anthus correnderd), yet Iceland, which is 

 10 nearer the pole, has, according to Mackenzie, fifteen land-birds. 

 The South Shetland Islands, in the same latitude as the southern half 

 of Norway, possess only some lichens, moss, and a little grass ; and 

 Lieutenant Kendall \ found the bay, in which he was at anchor, begin- 

 ning to freeze at a period corresponding with our 8th of September. The 

 soil here consists of ice and volcanic ashes interstratified ; and at a little 



* "Geological Transactions," voL vi., p. 415. 



f I have given details (the first, I believe, published) on this subject in the 

 first edition, and in the Appendix to it. I have there shown that the appa- 

 rent exceptions to the absence of erratic boulders in certain hot countries, 

 are due to erroneous observations : several statements there given, I have 

 since found confirmed by various authors. 



$ Gtographical Journal, 1830, pp. 65, 66. 



