268 Address before the Association of American Geologists. 



hints, therefore, may afford some feeble aid in the great work of 

 tracing out the systems of elevation that exist on this continent. 



I have alluded to some peculiarities in the Green Mountain sys- 

 tem of strata; and if I may venture a little longer upon your pa- 

 tience, I will ask a few moments' attention to what I must regard 

 as one of the most remarkable features in American geology. 

 Still, I have so imperfect a knowledge of the subject, as to be 

 conscious of venturing forward with few landmarks to guide me, 

 into an almost unknown region. I am aware, also, that there 

 are gentlemen before me, who have given the subject more atten- 

 tion than I have, and who are perhaps prepared for its full devel- 

 opement. 



We have all read of the enormous dislocations and inversions 

 of the strata of the Alps ; and similar phenomena are said to exist 

 in the Andes. Will it be believed, that we have an example in 

 the United States on a still more magnificent scale than any yet 

 described ? I have mentioned in another connection, a series of 

 strata, consisting of gneiss, mica, talcose, and argillaceous slates, 

 with limestones and Silurian rocks, extending from Canada, along 

 the western side of New England and the eastern side of New 

 York, to the Highlands on Hudson river, and thence southwes- 

 terly through the Appalachian mountains as far as Alabama; a 

 distance of at least twelve hundred miles. Along a large part of 

 this distance, a remarkable apparent inversion of the dip exhibits 

 itself; so that the newer rocks appear to pass beneath the older 

 ones ; and that too over a great width of surface. Certainly this 

 is the case from Canada to New Jersey, and thence through 

 Pennsylvania and Virginia, I infer from the reports of the Profes- 

 sors Rogers, that similar phenomena occur, which these gentle- 

 men have been studying with great care and success ; and the 

 results, I learn, will soon be given to the public. The effects of 

 the extraordinary agency under consideration, has not been sim- 

 ply to toss over the strata, so as to give them an inverted dip, but 

 in general to produce a succession of folded axes, with a gentle 

 slope and dip on their eastern sides, and a high dip, or more fre- 

 quently an inverted one, on their western side. 



Such a disturbance as this would be far less remarkable, were 

 it not so extensive. I cannot describe the width of the belt that 

 has been thus plicated, except in that portion of it which has 

 fallen under my notice. It appears to me, that in the latitude of 



