264 Address before the Association of American Geologists. 



The remarkable fertilizing power of green sand, first discov- 

 ered in this country, has raised another question in agricul- 

 tural chemistry, of great practical interest, concerning which, 

 there is not so much of an opposition, as of an unsettled state of 

 opinion. The question is, which of the ingredients of this sub- 

 stance produce the fertilization. All will agree, probably, that 

 the potassa found in some green sand, acts an important part. But 

 if this is the only ingredient, then the green sands of New Eng- 

 land and old England, will be of no agricultural value, as they are 

 destitute of potassa. But others suppose that the iron exerts a 

 favorable infiaence ; and others, that the mijiutely divided state 

 of the silica is important ; as it seems to be in the Bergmehl, 

 which is also useful in agriculture. But I have time only to ex- 

 press the confident expectation, that some of the gentlemen who 

 hear me, will, ere many years, clear up this subject. 



Had not these subjects been so intimately connected with sev- 

 eral of the state surveys, they might seem irrelevant on this occa- 

 sion. I return, therefore, to one more appropriately geological. 



But little has yet been published respecting the anticlinal and 

 synclinal axes and their correspondent systems of strata in our 

 country ; although I doubt not that numerous facts on the subject 

 are in the note-books of our geologists, in respect to the particu- 

 lar sections of country which they have examined. But this is 

 one of those subjects upon which, as upon diluvial action, gene- 

 ral results, applicable to the whole country, can be made out only 

 after long examination ; it is one, therefore, peculiarly proper for 

 such an association as I now address ; — and I predict, that when 

 the facts from difi'erent parts of this continent are collated and 

 compared, it will be found that we have some of the most re- 

 markable and magnificent systems of elevation and depression 

 on the globe. There is no small reason to believe, indeed, that 

 on the western side of this continent, from Cape Horn to the 

 northern Arctic Ocean, one vast anticlinal axis exists, along the 

 crest of the Andes and the Rocky Mountains. Subordinate and 

 perhaps intersecting systems of strata will undoubtedly be found 

 along this extended line ; but this appears to be the great con- 

 trolling and probably the most recent uplift on the continent. 

 The occurrence of volcanic vents along the whole line, while 

 they do not exist in the eastern part of the continent, renders it 

 probable that the former has been upheaved at a later epoch than 



