ad. D. Dana—Note on the Bernardston Helderberg Formation. 879 
Art. XLII —WNote on the Helderberg Formation of Bernardston, 
Massachusetts, and Vernon, Vermont; by JAMES D. Dana. 
IN examinations of the Bernardston Helderberg formation 
which were the basis of my former paper “On the Rocks of 
the Helderberg era in the Valley of the Connecticut”* my 
main purpose was lithological—that is, to ascertain and point 
out the kinds of crystalline rocks that were comprised within 
terranes of Helderberg (later Upper Silurian) age. he con- 
formable position of the Bernardston limestone beneath strata 
of quartzyte and slate, first made known by Professor Edward 
Hitchcock,+ I found to be, as I thought, a fact; and from 
there I traced the quartzyte at intervals, along with the slate— 
a peculiar mica slate easily distinguished by the minute garnets 
which gave its layers a pimpled surface, and the small crystals 
of mica set transversely to the lamination—over the country, 
to South Vernon in Vermont; and announced in my- paper 
that the Helderberg formation included, besides the quartzyte 
and mica slate, beds of compact green hornblende rock, a rock 
of the composition of syenyte, staurolitic mica slate, coarse 
mica schist, whitish and grayish quartzose gneiss, and all 
Stages of passage between quartzyte and gneiss. 
Recently, Professor C. H. Hitchcock, in the Second Volume 
of his Report on the Geology of New Hampsbire,t and more 
briefly in a note in this Journal,$ has suggested that the order 
of stratification at the limestone locality is not the true order; 
that the rocks may be “in an inverted position :” that the 
limestone stratum may have overlaid both the other formations, 
that is, the quartzyte and mica slate;| that “the limestone 
occupies a small valley in the quartzyte."§ Having, throug 
this supposition, made the limestone*the newest of the forma- 
tions, he concludes, further, that the mica slate, now lying over 
it, is not necessarily Helderberg; that the hornblende rocks 
and gneiss of Vernon are not necessarily of the Helderberg 
series,** and neither the staurolitic slate; that a long period 
-* This Journal, IIT, vi, 339. 
po etc. of Massachusetts, by E. Hitchcock, 8vo, 1833, 
Pp. 255; Report of Amer. Assoc. for 1851, p. 299; Report Geol. of Vermont, 
2 vols. 4to, 1861, p. 447. This last notice was prepared in conjunction with Mr. 
C. H. Hitchcock. It gives a section representing the limestone dipping bene 
quartzyte and slate. 
Page 428 and beyond, 1877. § Vol. xiii, page 313, April, 1877. 
Tbid. Report New Hampshire, vol. ii, p. 455. 
It should be added here that the volume of the N. Hampshire Geological 
Report referred to conveys on an earlier page (p. 18), a different opinion as to the 
limits of the Helderberg, where it is stated that the Connecticut Valley Helder- 
series consists of several thousand feet in thickness of qu 8 stones, 
slates, conglomerates, sandstones, flags, and probably hornblende schists. 
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