l28 LltfiRAfCRE ON TOR&teNfS. 



escaped in those, having befallen these, having been suggested or been called 

 in to support the theory or hypothesis. M. Costa, looking to the torrential 

 phenomenon of transport of material en masse, differs from M. C6zanne only, 

 or chiefly, so far as to attribute the whole, or by far the greater part of the 

 deposits in question, which are extensively distributed over some parts of 

 France, to torrential action alone ; maintaining and citing in support of his 

 views phenomena of torrents established by his previous observations which 

 go to prove that torrential action is equal to the production of all the 

 phenomena of these deposits, — the transfer of the blocks of the greatest 

 magnitude seen, and the transfer of these and of lesser stones without 

 damage to their angular outlines, and to the deposit of them where they 

 are, and in the form in which they are found. 



He does not deny that the effect of glaciers is what it is believed to be, 

 but he alleges that torrents, charged and surcharged with earthy matter, 

 bear off rocks and stones, and such earthy matters, in certain circumstances, 

 in a somewhat viscid mass, in which each constituent part may be con- 

 ceived of as retaining its relative position very much as such matters do in 

 a glacier, and therefore with their angularities unbroken. But in regard 

 to the composition and contour of the beds of deposit, he cites observations 

 of M. C6zanne and of his own which seem fully to warrant a conclusion 

 drawn by him from them, that all moraines — deposits chiefly associated 

 with glaciers — have not been produced by these, some having been pro- 

 duced by landslips and avalanches, if not otherwise, but that all cones of 

 dejection are the products of torrents. But he goes further, alleging that 

 while the melting or breaking up of the ice is only an accidental and local 

 phenomena, torrential phenomena are common and universal, and are so to 

 such an extent as to make the term torrential era objectionable ; torrential 

 force being a force which not only has manifested itself in a permanent and 

 continuous manner within and throughout the historic period, in modern 

 alluvia, and in the geologic period, in ancient alluvia— buried, some of them, to 

 the greatest depth ; but also in what may be called the cosmogonic period, 

 at every instant of the earth's life exercising an influence on the very 

 contour of the globe, if not also acting in the sun and in the planets. 



Such are the views entertained by M. Costa of such deposits as are described 

 in my citations from the work of M. C6zanne. 



And with all his enlarged and comprehensive views of torrential action, he 

 appears to have held the same views as those I have cited as the views of 

 Marschand and of Cezanne in regard to the later history of torrents in 

 France, to the extinction of these by the spread of vegetation, to the resusci- 

 tation of them by the destruction of forests, and to the re-extinction of them 

 by reboisement and gazonnement. 



Thus do all concur in pointing out to us the stage of the process in South 

 Africa, and in other newly settled countries, indicated by torrential floods, 

 when looked at in connection with the destruction of grass and herbage and 

 bush and trees witnessed in and beyond the portions colonized by Europeans. 



In regard to the means to be employed to secure the extinction of these, 

 he says,— "When the torrcntiality is feeble, and the evil consists mainly in 

 the quantity of the water, it is by bokemeid, and the spread of vegetation, 

 that it should be sought to effect the restrahit or extinction of it. If, on 

 the contrary, the torrentiality is extreme, and the devastations produced 

 by it proceed principally from the perturbations in the flow being now 



