ER&ATIC BLOCKS. 43 



the north of Europe, the weight of evidence unquestionably 

 is in favour of the supposition, that they have been transported 

 by masses of floating ice, which, on melting, dropped these 

 blocks in the then existing sea. On this point, among other 

 proofs, the evidence of M. Durocher, now professor at Rennes, 

 in Brittany, who has attentively studied these boulders as they 

 occur in the north of Europe, may be regarded as conclusive. 

 His opinions are in substance as follow: As the direction 

 of the blocks is usually from north north-west, to south 

 south-east, he conceives that in the first instance some 

 powerful erosive agency has disintegrated and destroyed the 

 mountains of the north, reducing their masses to blocks, 

 which have accumulated at their basis on the coasts then 

 in existence, while, at the same time, the rivers and streams 

 have tranquilly conveyed the smaller detritus into the sea. 

 During intense winters, masses of ice have embedded and 

 floated away these blocks; and such icebergs, on melting, 

 have deposited the blocks in various directions. The 

 elevation of the bed of the sea has subsequently brought 

 them to light. For some interesting observations on the 

 glacial furrows observed in the valley of the St. Lawrence, 

 and the action of packed ice in the Canadian rivers, the 

 reader is referred to Sir Charles Ly ell's travels in North 

 America,* First Series. " About three miles south of Hali- 

 fax, near * the Tower,' I observed,''' says this distinguished 

 observer, " a smooth surface of rock, formed of the edges 

 of curved and highly inclined strata of clay-slate, crossed 

 by furrows about a quarter of an inch deep, having a 

 north and south direction, and preserving their parallelism 

 throughout a space of one hundred yards in breadth. Similar 

 phenomena are observed in other parts of this peninsula. On 

 the removal of the drift, I observed a polished surface of 

 quartzose grit of the coal measures with district furrows 

 running E. and "W. or E. 15 N. magnetic." f 



THE GLACIAL THEOET. Among the agenda of the science, 

 or the questions yet to be proved, may be reckoned the 

 glacial theory of M. AGASSIZ. This philosopher, having 

 followed out the researches of Yenetz, Charpentier, and 



* Vol. i. p. 163. 



f For much interesting information on " Glacial Scratches," see Lake 

 Superior, its Physical Character, &c., by Professor Agassiz. 



