262 ERRATIC BOULDERS chap. 



June, and in a latitude corresponding with that of the Lake of 

 Geneva ! 



In Europe, the most southern glacier which comes down to 

 the sea is met with, according to Von Buch, on the coast of 

 Norway, in lat 67°. Now this is more than 20° of latitude, 

 or 1230 miles, nearer the pole than the Laguna de San Rafael. 

 The position of the glaciers at this place and in the Gulf of 

 Penas may be put even in a more striking point of view, for 

 they descend to the sea-coast, within 'j'^ of latitude, or 450 

 miles, of a harbour, where three species of Oliva, a Voluta, and 

 a Terebra, are the commonest shells, within less than 9° from 

 where palms grow, within 4-|-° of a region where the jaguar 

 and puma range over the plains, less than 2^° from arborescent 

 grasses, and (looking to the westward in the same hemisphere) 

 less than 2" from orchideous parasites, and within a single 

 degree of tree-ferns ! 



These facts are of high geological interest with respect to 

 the climate of the northern hemisphere, at the period when 

 boulders were transported. 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 great unstratified formation of mud and 

 sand, containing 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 farther than 48° of latitude, 

 measured from the southern pole ; in North America it appears 



1 Geological Transactions, vol. vi. p. 415. 



