248 ROCKS IN ICEBERGS. [chap. xi. 



In this Sound, about fifty icebergs were seen at one time 

 floating- outwards, and one of them must have been at 

 least 168 feet in total height. Some of the icebergs were 

 loaded with blocks of no inconsiderable size, of granite 

 and other rocks, different from the clay-slate of the 

 surrounding mountains. The glacier farthest from the 

 Pole, surveyed during the voyages of the Adventure and 

 Beadle, is in lat. 46° 50', in the Gulf of Penas. It is fifteen 

 miles long, and in one part seven broad, and descends 

 to the sea-coast. But even a few miles northward of this 

 glacier, in the Laguna de San Rafael, some Spanish mission- 

 aries * encountered * * many icebergs, some great, some small, 

 and others middle sized," in a narrow arm of the sea, on 

 the 22nd of the month corresponding with our 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 

 7^° 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 orchid- 

 eous 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 t 

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



* Agiieros, "Desc. Hist, de Chiloe," p. 227. 

 t ** Geologficsd Transactions." voL vL, p. 4.15. 



