368 Proceedings of the British Association. 



joiced that men with English feeling and English blood, should 

 be bringing them into operation. 



Sir H. T. De La Beche remarked, that the principal groups of 

 strata were separable all over the globe, and the physical condi- 

 tions which produced those deposits and governed the changes 

 of organic life must have been the same over large portions of 

 the globe also. He assumed a similarity of condition, not perfect 

 identity : those deposits were formed of the detritus of pre-existing 

 rocks, and as there were not equal conditions for producing and 

 carrying that detritus, there would be more striking deviations 

 from the general rule in one place than another ; the deposits 

 might have no representatives at all in time ; therefore to say 

 that one deposit was perfectly represented by another, would be 

 drawing conclusions without the necessary evidence. Both sec- 

 tions and fossils were necessary; but after all, we could only give 

 names to represent the state of our knowledge ; facts much more 

 numerous and much stronger than those on which our divisions 

 were founded, might compel us to alter all our names. The di- 

 vision of the older rocks into Carboniferous, Devonian, and Silu- 

 rian, should be retained as long as possible ; but the moment we 

 attained a sufficient body of evidence we must modify our views. 

 The different value of names in different parts of the world, ren- 

 dered it useless to attempt to make American deposits square ex- 

 actly with our own ; our definition of carboniferous limestone 

 would not apply to Ireland; a fortiori, we could not expect it to 

 coincide strictly with America ; and lastly, we should endeavor 

 to make our nomenclature as effective as possible for distinguish- 

 ing grouping formations in all parts of the world, so as to make 

 the terms comparable. 



On the Action of the North American Lakes ; by Mr. H. School- 

 craft. Mr. S.'s observations on these lakes were made during a 

 residence of nearly twenty years in that district, chiefly in the 

 immediate vicinity of Lake Superior, and he was thus enabled 

 to devote particular attention to the action of the lakes on their 

 boundaries, under fluctuations of level by which they have been 

 either considerably enlarged, or otherwise modified. In this re- 

 spect Lake Superior, perhaps, affords more scope for observation 

 than any other ; its large area and great computed depth, seem 

 more fully to develope the action of its waves upon the sand- 

 stone rocks which surround its southern margin. This is no 



