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Show 612 ADDENDA. shells not existing there. We may also suppose that he had discovered that the limits of the more tropical forms, both animal and vegetable, of the productions of the land, had likewise during this former period extended further south: what, then, would he say? Would he not at once infer, with the strongest appearance of truth, that the climate formerly had a more tropical character, properly so called, and therefore had a higher annual mean temperature than at present? Nevertheless, we know such an inference would have been absolutely erroneous. To put the case in another point of view : should a geologist find, in lat. 39°, on the coast of Spain, a tertiary deposit, abounding with Olivas, Volutas, and Terebras; or in lat. 45°, on the coast of Prance, other beds, containing a large Voluta, and numerous Patella:!, Fissurellffi, Chitons, and Balani, larger and of stronger growth than the existing species, would he be justified, after what is now known, in pronouncing that the climate formerly had a higher mean temperature? I think it may be safely asserted that he would not be so justified, but rather would be bonnd to search for other evidence. In the actual case of Europe, we have knowledge (as will be shown in a following note*) of another element in the problem, namely of the lower descent during former times of the snow-line,-as is inferred from the former low descent of glaciers, on the same mountains, where they now occur only at great heights, and likewise from the congelation during this same period of the soil in a low latitude-and this new element, I believe, gives the key to the solution of the problem, which is, that the climate of Europe was formerly more equable, but so far from being strictly more tropical, that it probably even had a lower mean annual temperature than it now possesses. I need scarcely say that I here refer only to the later tertiary periods : in the more ancient epochs, the plainest analogies tell us of an equatorial climate, whilst on the other hand, we are very far from having the smallest reason to supu pose that the snow-line then descended low ; and this is the key, as !have called it, to the problem of later times. Page 282. With respeet to Ice transporting fragments of rock in the Antarctic regions, M. Cordier, in his instructions (L'Institut, 1837, p. 283) to the voyage of the Astrolabe and the Zelee, has this passage : " Les relations de !'expedition anglo-americaine de decouverte executee en 1830, nous ont * As these notes are appended to the Journal, I have found it scarcely possible to classify them properly. I have been obliged to allude to the lower descent of the glaciers in Europe during former periods-facts which are first brought forward in a succeeding note to p. 294. ~DDEi\'DA. 613 fait connaltre qu~ les plages des Nouvelles-Shetland sont couvertes de g~a~ds blocs erratiques form es de granite, et par consequent d'une natme ~~tlei~e~t~ des, a~It.rcs roches dL~ ~ays. M. James Eights, naturaliste de xpeditJOn, n hesite pas a considerer ces blocs comme ayant etc apporte par les_glace.s, qui.viennent annuellement s'echouer et se fondre sur Ic: p~ages aont tl ~agit et COmme etant les indices de terres inconnu('S sitiH!es P us pres du pole que la terre la Trinite." I have not been able to find any ~ccount of th.is expedition. .Lie~ tenant Kendall describes ( Geogtaph. Jownal, 1830) pmnacles of syemte m Smith's Island, one of the South Shetland group; so that the inferences regarding the distances, from which the blocks ~re supposed to have come, probably are eiToneous. . In speakmg (p. 272) of the rigour of the climate of DEception Island m South Shetland, I might have mentioned that Lieut. Kendall says {_Geograph. Journal, 1830, p. 66), that on March the 8th, "We took the h10~ o:the freezing over of the cove (lat. 62° 55') and effected our retreat." Tin~ ~s the s~me as it: in the northern hemisphere, the barbom vf Clmstmnsund m Norway, were to freeze ou th~ 8th of September! Page 285. I have described the dimensions of the great glacier which in lat. 46° 50', sends down an arm to Kelly Harbour, and another to a flat s':amp; I now .find from information communicated to me by Captain FitzRoy,. that 1t must ~ommnnicate with the channels and bays north": a:d, whiCh extend behmd the peninsula of Tres Montes. Agueros, in g~vmg an account of an expedition of the missionaries ( Descripcion llistonal de Ia Provincia de Chiloe, p. 227 ), says, they encountered in the Laguna de San Rafael (lat. 46° 3:J' to 46° 48') "many icebergs (nmchos fm·~llones de nieve), some great, some small, and others middle sized." This .was on the 22d of November, 1778. Captain FitzRoy also tells me, that ~~ the account of another missionary voyage, it is said that the boats had difficulty, on account of the islands of ice, in passing through the Cano de Perdo~, a strait connecting the Laguna de San Rafael, with the other bays belund Tres Montes. Transposing in imagination, as I have done at P· 291, the places in the southern hemisphere to corresponding ones in Europe, these facts are the same as if, in a channel of the sea stretching from the Mediterranean between the Alps and the Jura, a boat should encounter in the latitude of tile lake of Geneva, and on the 22d of June, (but not on one occasion only,) so many icebergs, and of such dimensions that the historian of the voyage should describe them as being " some ~reat, some small, and others middle sized" ! Having insisted so strongly, in this part of my Journal, that it is in the;> southern hemisphere, where tropical forms encroach on the tcmpetate |