and contemporaneous Deposits of South America. 421 



but in the area, near the eastern mouth of the Strait of Magellan, where the 

 finest sediment has been arranged in horizontal laminse, and the coarse shingle in 

 beds, it appears strange that stratification should be so entirely, and often suddenly, 

 absent in the till alone. The mere dropping of the fragments seems hardly suffi- 

 cient to explain this ; for we have seen that both angular and rounded fragments 

 sometimes occur imbedded in the finest laminated matter. Perhaps the disturbing 

 action of the icebergs when stranded, as suggested by Mr. Lyell, may account for 

 this remarkable deficiency of stratification in the till. 



I will only further add, that I looked in vain for any marine remains in these 

 till-deposits, and a similar deficiency has been remarked in those of Europe. We 

 must not suppose that their absence can be accounted for by a bottom of this 

 nature being unfavourable to the existence of marine animals, for both in the re- 

 tired and only partially protected bays of Tierra del Fuego, kelp {Fucus giganteus) 

 grows in a depth of from two to twenty fathoms on the loose round stones, and 

 between the roots of the kelp innumerable creatures live : in the open sea also, 

 where there was no kelp, I found numerous Terebratulcs and other shells, on stones 

 lying in mud. But when we reflect how great a number of icebergs, some 

 charged with foreign matter, but very many more without any, must, on the above 

 theory, have been drifted to the spot while the till was accumulating ; and that 

 these icebergs being lifted up and down by the tides, as well as being broken into 

 pieces and many times stranded, would plough up large tracts of the bottom of the 

 sea, part of the difficulty in explaining the absence of marine remains in the till is 

 removed, for we can hardly conceive the existence of any animal on a soft bed of 

 mud and stones, disturbed at intervals with great violence. 



An interesting description is given by Wrangell* of the fragments of ice oflf 

 the coast of Siberia, often raised into a vertical position, and which, to use his 

 words, " are driven against each other with dreadful crashes, are pressed down- 

 wards, and reappearing again on the surface covered with the torn up green mud, 

 which we had often seen on the highest hummocks." The particular case thus de- 

 scribed happened 100 miles from the main-land, where the water however was only 

 about fifteen fathoms deep : many of the hummocks were about 100 feet high. 

 Wrangell states, that within the line of large hummocks the sea was generally tran- 

 quil, and strewed with only small fragments of ice ; so that in this case undisturbed 

 strata of gravel or other matter might easily (during the gradual elevation of the 

 land, believed to be there in progress) accumulate over the disturbed beds ; and in 

 these latter deposits it is not probable that any organic remains would be enclosed. 



There are two sections at Gregory Bay, in the eastern part of the Strait of 



* Wrangell's ' Voyage to Siberia and the Polar Sea,' translated by Major Sabine, p. 257- 

 VOL. VI. — SECOND SERIES. 3 I 



