334 The Drift or BonMer Formation, 



observations in the United States and in Europe. In addition to 

 this it can be shewn that in some districts where there are groups 

 of high mountains the boulders have travelled in all directions 

 away from one of these hills, which is therefore called a centre of 

 dispersion. We have not ascertained that any such centres exist 

 in British North America, although they have been found in the 

 Eastern States. These centres of dispersion must be regarded as 

 mere local phenomena, confined to comparatively small tracts of 

 country, while the glacial drift, in its widest sense, appears to 

 have been a grand process, extending its operations over the whole 

 northern hemisphere, in a continuous sheet, flooding the earth, 

 sweeping along huge boulders from the north towards the south, 

 and scouring, polishing and grinding down all the formations over 

 which it passed. 



Theories of the Drift. — The theories that have been devised 

 in order to account for the phenomena of the drift are principally 

 the following : — Some Geologists have supposed that in conse- 

 quence of a great subterranean convulsion the bottom of the sea 

 at the north pole was suddenly elevated, and the superincumbent 

 waters caused to rush violently southward over the continents, 

 dashing among the hills, tearing up rocks, and carrying the ruins 

 along with them in their tumultous career. This, we believe, is 

 called the " debacle theory," and the flood caused by the elevation 

 of the sea-bottom, the " the debacle or wave of translation."* 

 The objections to this theory are that while it is purely hypo- 

 thetical, there is, besides, evidence that the work of polishing and 

 grooving rock surfaces appears to have been a slow operation, 

 instead of a rapid and violent one. It is evident that the worn 

 and completely rounded condition of the greater number of the 

 boulders must have been produced by the long continued action 

 of water. A disturbance that could only continue for a few days, 

 or while the wave was passing over the continent, must have been 

 utterly incompetent to produce even a tenth part of all the pheno- 

 mena that may be observed in connection with the drift. 



In a work published in Paris in 1844, {Etudes sur VHistoire de 

 la Terre,) the author, M. de Boucheporn, accounts for the erratic 

 blocks of Europe by supposing a sudden displacement of the axis 

 of the earth, in consequence of which the North Pole was brought 

 to take a position in the neighborhood of the Baltic Sea, 

 somewhere near and north of Prussia or Poland. But as 



* From the French debacle, the breaking up of a frozen river. 



