Qeology and Mineralogy. 



We here leave the volume, 

 ing American and other igneo 

 in every part by those who would fully understand their nature 

 and relation. tT ly D 



3. Note upon the Connecticut Valley Helderberg ; by C. II. 

 Hitchcock. (Communicated.)— At the close of au article upon 

 _ rocks in New Hampshire (this Journ.. III. vol. vii, p. 

 5/1), I proposed to discuss later the relations of the Bernardst'on, 

 Mass., Helderberg limestone to the associated rocks in Hinsdale, 

 -V 11., and \ ernon, Vt. This has been done fully in the second 

 volume of the Geology of New Hampshire, which will he accessi- 

 ble to the public next June. I desire now very briefly to state 

 icipal conclusions. I. The associated quartzite and stauro- 

 Iite mica slates have been satisfactorily traced out to connect with 

 the Coos group of New Hampshire, "as was first suggested by 

 Prof. Dana (this Journ., III. voUi,,.. .)*>>). l\ The limestone does 

 not certainly dip beneath the quartzite. Had the section been 

 rods north the slates would be found to dip west ami 

 the quartzite standing on edge and the limestone concealed by 

 ?° • ^ n the west side of the limestone is a west dip in the quartz- 

 ite. These facts suggest the possibility of a different interpreta- 

 tion from that heretofore uuiversally given. The limestone may 

 oe a remnant of a once extensive deposit covering both the other 

 tarnations mentioned, and what remains i- in an inverted position. 

 •■ : "iie in Littleton overlies the quartzite. 3. If the Coos 

 lerberg strata are identical in age, the hornblende schist 

 ■l the oiieiss of Vernon are not necessariiv associated 

 ™ them, nor any ol reas - >t N ew England. 



Ane Loos si.-, , ,.],;, t j L . ( .} :1} s at s (Lower Silu- 



"■ " ' ■ . • -' i , . ■. ■ ■■;..-.. ■ :-: ■ 



ward, as first suggested by Prof. Dana. These same slates rest 



lntt 1 ■ e ^ uebec group of Logan in the Littleton region, and these 



r til" rj tUrn Upon the same g neissic group as in Vernon. 4. Next 



tne Helderberg the Coos rocks are the newest in the Connecti- 



' ! ■• >■ way to < atiada: ami if ihev can be proved iden- 



rad also to include the enormous calcareous 



otern Vermont and Canada, called "< alciferous mica- 



^nist m the Vermont Iieport, thev show that all tlie rest ol the 



orthern New England formations aiv older, and hence liable to be 



zoic series. 5. The Bern., dstou regi n bounds with 



th strata. It is impossible to propound 



| :■ [hem. The same 



the whole of New Hampshire. 6. Further search in 



r "n region enables me to correct t\^ statement of my 



Previous artich . I ;l :n satisHed that all the clay slates of Litth ton 



♦h * Samo a g e with those (,i V * at lea8t 



tap (p. 471), 



th tj transf, en-ed to the other series. 7. The kinds and order of 



nati erber S rocks are essentiail J - "^ Ber " 



raston fields ; hence, by comparing the facts in both regions better 



