90 



THE GEOLOGIST. 



panied by heaps of diluvial matter. The erratic blocks 

 were generally either of granite or gneiss ; but between St. 

 Petersburg and the Niemen^ no less than fourteen different 

 kinds of rock were found, all the known sites of which were 

 in Finland. These blocks were sometimes twenty and 

 twenty- five feet in thickness, and their angles by no means 

 rounded or worn. The Volga is the most eastern limit in 

 which these blocks are found. The granite blocks, how- 

 ever, appear to have been carried to greater distances than 

 those formed of limestone. Another circumstance to be 

 remarked was, that these blocks lie either in or upon vast 

 deposits of sand, or diluvial matter regularly stratified in 

 nearly horizontal layers. This showed that the sand had 

 been deposited in a sea not greatly agitated, and therefore, 

 the supposition that the blocks had, in all cases, been carried 

 by a violent diluvial current, Avas not admissible. It was 

 probable, Mr. Durocher thought, that these blocks had been 

 floated on ice fields, and had been deposited at the bottom 

 of the sea by the melting of the ice. At the same time, he 

 thought it evident that an immense diluvial current, the ori- 

 gin of which there was as yet no means of conjecturing, had 

 taken place ; that it had commenced very far north ; that it 

 was probably accompanied by an immense quantity of float- 

 ing ice, and that it had spread over all that part of Europe 

 comprised between Greenland and the Ural mountains in 

 Russia. The current had been turned southwards covering 

 Sweden, Norway and Finland, breaking off* rocks from the 

 mountains as it passed along ; polishing the surface of the 

 rocks, and leaving streaks on them from the action of the 

 sand, stone, and rocks when it rolled onwards. The current 

 had extended into Germany, Russia and Poland, but its 

 force had apparently become weaker as it went further 

 south; towards the east it had been lost in the plains 

 of Russia and in Germany, has been stopped by ranges of 



