2 
268 J. D. Dana—Southward ending of o 
fast gaining ground. It seems probable that we here havea 
wide-spread and very interesting phase of metamorphism, the 
alteration of one rock to another resulting from the change of 
of the paramorphism of pyroxene, or, indeed, that it is ever 
eed necessary. e range of observations is as yet too 
small to allow of any generalization. These thoughts are 
tien net as suggestions and it will in future be interesting to 
_ note whether this change has taken place on as large a scale, if 
at all, in the rocks of undisturbed regions, as in those whic 
show unmistakable signs of having been ‘subjected to great 
pressure. 
Johns Hopkins University, Baltimore, May 30, 1884, 
Art. XXXIV.—Oni the Southward ending of a ores Synch 
in the Taconic Range; by JAMES D. Dana. Witha 
(Plate IIT.) 
[Read before the British Association at its session in Montreal.] 
THE Taconic question, although American in its facts, bears 
no less profoundly on oe than on American geology ; for 
it is largely a question as to the age and origin of crystalline 
ocks. I have therefote thought the subject an appropriate 
one for a meeting of the British Association. 
My stratigraphical work in the region of the Taconic Range, 
begun in 1870, I have continued during the last two years; 
. and it is my saan to present some of the results of my 
recent investi 
The acaadio with regard to the Taconic rocks has been 
reatly ee Se from the first, by Professor Emmons'’s 
extension of the term Taconic to the rocks of other regions 
besides those of fie original Taconic, because they were sup- 
sed to be—not proved to be—supposed to be of the same age 
and system. My work has been among the original Taconic 
rocks, those of the Taconic Range and its bordering limestone, 
which, together, gave to geology, through Professor Emmons, 
the term Taconic and the first facts and conclusions on the 
subject ; and of these alone I speak. 
aconic Range extends along the western border of 
New England, between Middlebury in central Vermont on the 
north and Salisbury in northwestern Connecticut on the souta, 
and encroaches by its western slopes a little on the State és 
New York. The distance between these points is about 1 
