428 Mr. Darwin on the Boulders 



low perpendicular cliffs of ice. The surface of these glaciers, even to a considerable 

 height on the mountains, was of a bright azure colour and perfectly clean, as 

 were the floating fragments. This is what might have been expected, from the 

 shortness of the glaciers, from their not being bordered by precipices, and from 

 their not being formed by the junction of two or more smaller streams of ice. 

 Although the chief characteristic of the climate of the southern parts of South 

 America seems to be its equability, yet the glaciers cannot descend very slowly, 

 for large masses are continually breaking from the clifFs of ice. We were witnesses 

 of one fall in the Beagle channel ; and the water was strewed with smaller pieces : 

 Capt. King* mentions several bays and channels in Tierra del Fuego almost 

 choked up with them; Mr. Bynoef informed me that as many as fifty icebergs 

 were seen together in Sir G. Eyre's Sound : behind the peninsula of Tres Montes, 

 in a latitude corresponding to that of the lake of Geneva, some Spanish mission- 

 aries!, in an account of their voyage, describe an arm of the sea as crowded with 

 icebergs of all sizes. Some of the fragments of ice which are thus detached are of 

 immense size : Mr. Kirke§ met with one in an inland creek, situated in the corre- 

 sponding latitude as Paris, which was estimated at forty-two feet in height, and 

 was aground, where bottom could not be obtained with a line of 126 feet. This 

 mass was therefore at least 168 feet in height, equal to a lofty church: how vio- 

 lently must the tranquil waters of the retired creek have been agitated when it fell ! 

 Capt. King, describing another caseH, compares the crash to a broadside reverbe- 

 rating through these lonely regions. In the Beagle channel the insignificant fall 

 which we witnessed, caused a wave that nearly destroyed our boats, though hauled up 

 on the shore, and at the distance of half a mile from the cliff" of ice. These waves 

 seem to displace and drive before them the fragments of rock lying on the beach. 

 Although the glaciers I saw were quite clean, many of the icebergs described by 

 Mr. Kirke in Sir G. Eyre's Sound were dark coloured, and on the surface of one, 

 several blocks of granite and serpentine were found. 



The glaciers in the Beagle channel were generally bordered by a tongue of land, 

 formed of huge fragments of rock, and many boulders were strewed on the neigh- 

 bouring shores. The only glacier which I approached closely, descended to the 

 head of a creek, formed on one side by a wall of mica-slate, and on the other by a 

 broad promontory, about fifty or sixty feet high, and apparently composed entirely 

 of enormous fragments, chiefly of granite. One of these was ninety feet in cir- 

 cumference, and projected six feet above the sand. This promontory, which 

 originally no doubt was a lateral moraine, projects nearly half a mile beyond the 



* Voyages of the Adventure and Beagle, vol. i. pp. 56, 58, 140, 258. 



f The Author's Journal of Researches, p. 283. § Voyages of the Adventure and Beagle, vol. i. p. 337. 



I Ibid., Appendix, p. 613. || Ibid., vol. i. p. 140. 



