350 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [April 8, 



at which I had previously arrived, and still further elucidating the 

 subject. 



The superficial phoenomena of Sweden are so remarkable, that, to 

 say nothing of native authors, few foreign geologists have visited 

 that kingdom without recording the impression which their inspec- 

 tion produced. M. Alex. Brongniart published in the year 1828 a 

 memoir* on the erratic blocks of Sweden, in which, referring to De 

 Luc, De Saussure, and others who had treated generally of the distri- 

 bution of coarse detritus, he cites MM. Escher and von Buch (parti- 

 cularly the latter) as having well considered the northern examples. 

 In this memoir M. Brongniart, after describing the linear form of 

 the Osarf, and the size, form and nature of their materials, specially 

 calls attention to the fact, that their chief mass is composed of com- 

 pletely rounded water- worn gravel, often very coarse and containing 

 boulders of some magnitude ; and states, with perfect accuracy, that 

 the largest blocks invariably overlie the great heaps of detritus. But 

 although he also truly says that some of them are angular, he does 

 not convey to his readers the important fact, the result of my own 

 investigations and those of my friend, that such large blocks as are on 

 the surface are invariably more or less angular, and are quite distinct 

 from and never intermixed with the rounded and highly triturated 

 debris on which they rest. 



At the period when M. Brongniart wrote, geologists had no mode 

 of explaining the transport of all sorts of detritus, except by assu- 

 ming the powerful action of water in the manner supposed by De 

 Saussure, De Luc, Sir James Hall, and numerous other authorities, 

 among whom M. Brongniart cites our distinguished countrymen 

 Buckland and Sedgwick, both of whom, with the rest, then attri- 

 buted such transport to a more powerful agent than any now known 

 in nature. 



Another superficial phaenomenon dwelt upon by M. Brongniart 

 was the mechanical striation of the Swedish rocks in lines from north 

 to south, or as he thought, generally from N.N.E. to S.S.W.; in re- 

 ference to which he quotes De Lasteyrie, who not only remarked 

 the same fact thirty years before, but also observed, what indeed 

 M. Brongniart did not remark, that the northern ends of certain 

 rocks and promontories were rounded and worn, and their southern 

 sides left rough. The observation of De Lasteyrie is that which 

 M. Sefstrom at a subsequent period so extended as to render it pro- 

 bable that the phaenomenon might be considered general in respect 

 to all those parts of Sweden which he visited, and in memoirs com- 

 municated to the Academy of Stockholm he showed that long ridges 

 of detritus of northern origin were almost invariably to be seen ex- 

 tending from the southern or abrupt side of each rocky promontory 

 whose northern face was worn down and striated, and observed that 

 such results had probably been produced by a powerful deluge pro- 



* Ann. des Sciences Naturelles. 



t " Osar" in Swedish is the plural of " Os," a heap or ridge of water-worn 

 detrital matter. 



