The Glacial Theory. 



131 



the results of their enquiries, and we here propose to offer 

 an outline of the present state of the question. 



The glacier theory, says Professor Forbes, Edinburgh New 

 Philosophical Journal, No. 63, page 85, whether it regards 

 the present or the past history of those mighty and resistless 

 vehicles of transport and instruments of degradation, yields 

 to no other physical speculation of the present day in gran- 

 deur, importance, interest, and I had almost said, novelty. 

 It is, says M. Agassiz, scarcely any longer a mere theory ; 

 it rests on a whole series of phenomena apparently very 

 different, but whose relations are evident to all observers : 

 these are the erratic blocks, the mounds of loose materials, 

 the ancient moraines, the polished and striated surfaces, the 

 furrowings of rocks in a constant direction, which facts have 

 been emphatically named the erratic phenomena. 



" Since the domain of observation has been fairly entered," says M. 

 Agassiz, " the investigation has advanced with gigantic strides. The 

 beauty of the subject, the vast field which it embraces, the exciting 

 questions belonging to it, have awakened on all hands, zeal, interest, 

 curiosity, and ambition. There is now not an academy, not a scientific 

 society, in which the erratic phenomenon has not been discussed and 

 supported by new facts ; and such has been the activity displayed by 

 the savans of every country, that the most succinct abstract of the 

 works and memoirs on the subject which have appeared within the 

 last two years, would greatly exceed the limits of an article like the 

 present. M. de Charpentier, in his Essai sur les Glaciers et le 

 Terrain Erratique, has described in detail the traces of ancient 

 glaciers in the great valley of the Rhone and its lateral valleys, and 

 also at a multitude of other points in Switzerland ; M. Studer has 

 observed them on the southern side of the Alps ; and Mr. Martins 

 in the Grisons. The French geologists assembled at Grenoble in 

 1840, studied them in the Alps of Dauphiny, and made them the 

 subject of their discussions at the meeting held at Lyons in 1841. 

 The pohshed rocks, in particular, seem to be very distinct on Mount 

 Cenis, where they have been detected by Mr. Trevelyan and by 

 Captain Le Blanc. MM. Renoir, Hogard, and Le Blanc have con- 



