Association of American Geologists and Naturalists. 1 5 1 



side of Vermont and Massachusetts, have been carefully studied by Em; 

 mons, Hitchcock and Mather, all of whom appear to have arrived at 

 different conclusions concerning them. Since the same or a very anal- 

 ogous group of strata ranges at intervals, holding the same relative po- 

 sition, the whole distance from Vermont to Georgia, the question of 

 their age, while it has a wide bearing on any general classification of 

 our formations, ought certainly to admit, sooner or later, of settlement, 

 when so many and such noble transverse sections are opened to inspec- 

 tion by the river gorges which cut the Blue Ridge. 



Prof. Emmons considers the granular quartz, slate and limestone of 



the Taconic hills and the Stockbridge valley, as constituting a distinct 



group of strata, neither appertaining to the true gneissoid or mica schist 



system on the east, nor to the palaeozoic fossiliferous rocks of the Cham- 



Plam and Hudson valley on the west, but holding an intermediate place 



« the scale of time. His principal argument in defence of this view, 



jst at the order of succession of the component members of the group, 



is essentially different from that witnessed in the sandstone, limestone 



■J s'ate of the Champlain division, and he denies that the theory of 



P 'cation of the beds, advanced originally by myself and my brother, 



applied to this very region, can reconcile the seeming want of agree- 



• JNow it is true that the apparent order of superposition in the 



aconic belt, is in discrepancy with the well known succession of the 



^amplain formations, but this is precisely what should arise from the 



' ro uction of those complete folds or doublings together of the strata 



k • k WG haVe conceived to exis * ? and I would add that the sections 



Wtmhed by Prof. Emmons and Prof. Mather in their reports, if resolved 



J the introduction of the flexures supposed by us, will all of them dis- 



y> or their western portions at least, the normal order of superposi- 



J° ° f the Champlain rocks. This identity of the so named Taconic 



em > Wi th the formations of the Hudson and Champlain valley, was 



jounced by my brother and myself, in the beginning of 1841, to the 



^erican Philosophical Society. By aid of a section from Stockbridge 



tne Hudson river, we showed the existence of numerous close 



"ticliml a 



of h synclinal folds, and thus explained the apparent inversion 



'P> which other geologists had ascribed to one general overturn- 

 tfae ft Wn ole series. The plication was shown to be greater along 

 w j e valle y an <* the ridges east, the granular Berkshire marble 



limestone 



jf,. , * "«? uiuc uuicsiuiil; vi mo i^uuwu yaucjr, uui mcia- 



, . a by heat, and the associated micaceous, talcose, and other 



ere referred in the language of the communication, to the slates 



< 



