170 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



lie the whole Green Mountain series, are of Trenton age, and 

 owe their apparent position to overturned folds, accompanied 

 in some places, apparently, by dislocations. In the province 

 of Quebec they are involved botli with the older crystalline 

 strata and the Upper Taconic, but farther south, in Vermont, 

 with the Lower Taconic series, which is, for the most part, 

 concealed between Lake Champlain and Quebec. The crys- 

 talline limestones of this latter series in western New Ens:- 

 land have, by different geologists within the last twenty 

 years, been referred to the Quebec group, to the Trenton, and 

 to the Niagara or Ilelderberg a history recalling that of 

 the similar limestones of Italy which is told in the last year's 

 Record (page xcix). In each case both stratigraphical and 

 paleontological evidences have been appealed to in support 

 of the various hypotheses, as in the similar and long-contest- 

 ed problems relating to the rocks of the Maurienne and Ta- 

 rentaise in the Alps. Fossiliferous strata included in folds, or 

 in faults, are supposed to lix the age of the entire series; and 

 the absence of fossils from the other parts of the section is 

 accounted for by the assumed metamorphosis of these por- 

 tions of the strata. In more cases than one in the history 

 of these rocks, forms not of organic origin have done duty as 

 fossil remains. It is instructive, in this connection, to note 

 the observation of Dana, that some slaty quartzites inter- 

 stratified with limestones in Vermont exhibited "forms that 

 looked exceedingly like casts of a Pleurotomaria and a Mur- 

 chisonia, and of a valve of Orthis lynx." These, however, he 

 admits to be only "imitative forms," due in some unexplain- 

 ed way to concretion. There are also, according to him, sec- 

 tions of long-chambered cylinders, as of "crinoidal stems, yet 

 having the chambers too large and irregular for any known 

 crinoidal forms." From supposed paleontological evidence, 

 he now refers the whole belt of Lower Taconic rocks to the 

 Champlain division, thus returning to the view long ago ad- 

 vocated by Mather, but rejected by Logan in favor of one, 

 and by Adams of another, hypothesis each of which lias 

 found its advocates in turn. 



GEOLOGY OF WISCONSIN. 



Irving lias discussed the subject (alluded to in the last year's 

 llecord) of the imagined Paleozoic age of the Huronian rocks 



