ScientMc Intelligence — Geology and Mineralogy. 177 



simple expression of which has been secured to science up to the pre- 

 sent time. 



\st, The phenomenon of striae and polishing of rocks, considered 

 in a general way, has preceded all the deposits of this epoch, and, 

 consequently, the development of the marine, lacustrine, and terres- 

 trial faunas. If these traces of friction have been produced by gla- 

 ciers, the shells called arctic, buried in the clays and sands which 

 cover them, are not contemporary with the period of greatest cold, 

 since they are found in the very place which the glaciers must have 

 occupied. Accordingly, these shell deposits, which seem to indicate 

 a lower temperature than what now prevails in the same latitude, 

 would likewise prove a more elevated temperature than that of the 

 epoch which immediately preceded them. 



2ci, As far as the existing documents permit us to conjecture, the 

 terrestrial fauna of the great mammiferous Pachyderms, Ruminants, 

 and Carnivora, would likewise be posterior to the phenomenon of 

 striae, and partly also to the shell deposits of which I have spoken. 

 The cause of its destruction could not therefore be, as has been alleged, 

 the low tempei-ature which produced the greatest extension of the 

 glaciers, unless these animals were found to belong to the superior 

 tertiary formation. But the latter presents very distinct zoological 

 characters, its end must coincide very nearly with this same period 

 of cold, and, in the centre of Europe, with the upraising of the 

 Alps of the Valais. This fauna of vertebrate animals, not less re- 

 markable for their size than for their rarity and the number of indi- 

 viduals, has lived, like the preceding shells, between the moment of 

 the strise phenomenon or of the greatest degree of presumed cold, and 

 the cataclysm which destroyed them almost simultaneously in Europe 

 and in Asia, in the two Americas, and Australia, and which have en- 

 veloped their remains in the sand, gravel, and rolled pebbles of val- 

 leys, as well as in the mud of caverns, where we now find them. 



ScZ, If the erratic deposits which enclose these bones have been 

 carried by currents arising from the melting of ancient glaciers, it 

 must necessarily be that these did not belong to the period of the 

 greatest cold ; they must then have been confined to the mountain- 

 ous regions to permit the development in the plains and lower grounds, 

 not only of the great mammifera, but also of a vegetation sufficiently 

 rich to nourish them. There would thus be a very sensible increase 

 of the temperature after the moment of the greatest cold represented 

 by the strise and most ancient polished rocks, a period, for the dura- 

 tion of which, we, as yet, pos.sess no chronometer similar to those 

 which geologists employ, and of which we can only assign something 

 like the commencement and the end. 



\th. The first erratic phenomenon would be exerted more particu- 

 larly in the northern zone of Europe and America, and its effects 

 would have been more general ; the second, affecting more especially 

 the temperate regions of the two hemispheres, has been subjected to 



VOL. XLV. NO. LXXXIX. — JULY 1848. M 



