200 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



lations over Northern Europe and North America of detrital matter, 

 in the form of sand, clay, gravel, boulders, and huge erratic blocks, 

 and of the grooved, striated and polished surfaces of hard rocks 

 vrhich usually accompany them. This great problem, complicated 

 in its nature and full of difficulties, has of late years more particu- 

 larly arrested the attention of geologists ; and it must long continue 

 to do so before a sufficient mass of observations can be collected on 

 which a satisfactory solution of it can be founded. Although, as 

 regards Europe, many important local facts, exhibited in limited 

 districts, have been well described by several geologists, both of this 

 country and of the continent, we are indebted for the most extended 

 observations and the most comprehensive views of the subject to the 

 labours of Keilhau, Sefstrom, Durocher, Murchison, De Verneuil, 

 and Forchhammer. The geologists of the United States, and Lyell, 

 have brought together a great body of evidence respecting the same 

 phaenomena in North America. There is reason to infer, from the 

 limited observations that have been made along the shores of Sibe- 

 ria, that the boulder formation extends also over Northern Asia. 



Many new observations have been made known to us during the 

 last year, by the authors of the ' Geology of Russia,' by Mr. Lyell in 

 his ' Travels in the United States, Canada, and Nova Scotia,' and by 

 M. Durocher in an additional memoir which he read last December 

 before the Geological Society of France, describing observations 

 made by him in Norway daring the preceding summer. 



You are aware that Agassiz and Charpentier have attempted to 

 explain the phsenomena by supposing, that at a very recent geologi- 

 cal period, since the time when the land had assumed its present 

 form, Northern Europe was covered with a vast mantle of ice, and 

 that the detritus and erratic blocks have been formed and transported 

 by the agency of sub-aerial glaciers, in the same manner as moraines 

 have been accumulated, blocks transported, and rocks furrowed, 

 striated, rounded and polished by the glaciers descending from the 

 Alps. Abundant evidence has been brought forward to demonstrate, 

 that by no such action can the phaenomena be explained ; and all 

 the geologists mentioned above, who have carefully investigated 

 them, reject the theory as inapplicable to Northern Europe and 

 America, except in a very limited sense. 



The Boulder Formation, or Northern Drift, and The 

 Erratic Blocks, are shown, by the authors of the 'Geology of 

 Russia,' to be two distinct classes of phaenomena ; the latter being 

 usually angular, the materials of the former being rounded and worn 

 by attrition. It appears to me to have been clearly proved that the 

 boulder formation is not the work of a sudden transient action of 

 short duration, but the result of operations that were going on during 

 the middle tertiary deposits, and in Europe extended at least to the 

 Pleistocene period ; that the greater part of the accumulations took 

 place since existing species of testacea inhabited the adjoining seas ; 

 and that the transport of erratic blocks took place at a later pe- 

 riod. It seems to be no less clearly established, that the boulder 

 and drift accumulations and the erratic blocks now covering the dry 



