THE PROGRESS OF GEOLOGY. 



xi 



downward movement of the glaciers ; which, cutting through 

 the deposit, throws up some portions into lateral and termi- 

 nal moraines. These opinions, however, throw light only 

 upon the present diminished scale of action of glaciers, and 

 tend to prove a diminution in size of the glacial summits of 

 the present day, not of sufficient extent to add weight to 

 M. Agassiz's theories of general centres of glacial action, 

 nor to invalidate the pre-conceived opinions of the conjoint 

 action of water and ice — the former being the agent, to which 

 detrital deposits have, in all times and at all eras in the 

 science of geology, been attributed — the latter being the 

 plausible lucubrations of comparatively modern philosophers. 

 At the close of 1842 it may then be said fairly that the 

 " diluvio-glacialists'' have the majority ; and that their 

 opinion is, that all those erratic blocks which lie scattered 

 upon the surface, were transported by the associated in- 

 fluences of water and ice, and deposited in their present 

 position, beneath the former, in an age and under circum- 

 stances, different and far removed from the present. 



The simplification of science is the last subject to which we 

 shall allude, as one of great importance in every way. We 

 have seen from the previous portions of the Report, that as 

 attention has been more especially directed to the older rocks, 

 so the result has been a recognition of types, by which the 

 line of distinction may in all cases be drawn with accuracy, 

 and hence may fairly be said to have accomplished a simpli- 

 fication of the arrangement of these beds : for, whatever may 

 be the nomenclature, it is to the facts themselves that we 

 must look in the first instance for carrying the point in 

 question. The glacial theory, on the contrary, we leave in a 

 labyrinth whence time alone can extricate it 5 we repeat 

 again, that we see but small probability of any great light 

 being thrown upon it, in its relation to the ancient phenomena 



