204 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



Icy Sea, in north-eastern, northern, and north-western directions; 

 and Norwegian detritus has been transported westward to the coasts 

 of Norfolk and Yorkshire. 



Russia in Europe, from the nature of its surface, cannot be sup- 

 posed to aftbrd many proofs of furrows grooves, and striae on hard 

 rocks ; but on Lake Onega a hard greenstone and siliceous breccia 

 are rounded off, grooved and striated on the northern face of a small 

 promontory, the direction of the grooves and striae being north and 

 south, and the striae are to be seen, through the transparency of the 

 water, eight feet below its surface ; they are also to be traced near 

 the summit of a low hill. On the south side of that hill, however, 

 no such traces of wearing or friction can be seen, " and thus," the 

 authors say, " we had before us, on the edges of Russian Lapland, 

 the very phaenomenon so extensively observed by Sefstrom over 

 Sweden, viz. a rounded, worn, and striated surface of the northern 

 sides of promontories, whose southern faces are natural and unaf- 

 fected by any mechanical agency." 



M. Durocher visited the coasts of Sweden and Norway, in the 

 neighbourhood of Christiania, last year, and discovered there many 

 most remarkable instances of these furrows and striae, detailed ac- 

 counts of which he has given in the paper read before the Geologi- 

 cal Society of France, in December, which I have already alluded 

 to. He indeed describes effects of erosion on a much greater scale 

 than I remember to have read of before ; furrows so deep, that chan- 

 nels are a more appropriate term ; as he himself has thought, for he 

 calls them canaux. Both on the east and west coasts of the bay at 

 the head of which Christiania is situated, from Gothenborg on the 

 Swedish shore, and from Arendal, on the Norwegian, to Christiania, 

 distances of 160 and 170 miles respectively, and especially among 

 the islands that skirt the Norwegian coast, he observed the rocks 

 worn into deep channels and furrows, or striated, in directions from 

 north-west to south-east, and having their surfaces rounded and 

 polished. These channels or furrows are of various dimensions; 

 some from twenty-five to fifty centimetres (ten to twenty inches) in 

 width, with a depth of from one and a half to two and three metres 

 (five to ten feet). In a great number of instances the sides of the 

 interior of these channels are grooved and striated in the direction 

 of their longer axis. Sometimes they divide into two or more 

 branches, which afterwards reunite into one. Many are rectilinear, 

 but many are undulating, and bent in short waves. The axes of 

 the channels and the striae in their interior have the same general 

 direction as the depressions of the neighbouring country. The 

 north-western extremity of these channels, that is, the openings 

 made where the eroding instrument entered, are somewhat wider 

 than the rest of the channel, and are rounded off, polished, and 

 striated. 



Another very curious, and, as far as I know, a new class of facts 

 has been described by M. Durocher. These furrows, he states, are 

 frequently met with in horizontal lines on the under side of over- 

 hanging rockS) and he has met with instances of this description 



