416 J. D. Dana—Taconic Rocks and Stratigraphy. 
Taconic limestones. In 1844, 1846, he dropped the argument and 
the conclusion, and showed, by sections, how through flexures 
the order of original superposition might be reversed. This 
change left the Sparry limestone and Taconic slate older, as be 
fore, than the Potsdam. Further, he added the Black slate of 
Washington Co., N. Y., with its trilobites, and made this the 
upper or newer member of the series, on account of the fossils, 
with the other members following in the descending order above 
given,—the quartzyte at the bottom. 
Professor Emmons was right in his Berkshire stratigraphical 
observations. He drew chronological conclusions on data that 
we now know to be too uncertain for any sate inference, and on 
lithological data extended his system beyond its true limits; but 
in those decisions at that early time there is nothing to his dis- 
credit, while his investigations are greatly to his honor. 
It is a fact of historical importance in the Taconic controversy, 
that the writings, on the subject, by Professor Mather, the Pro- 
fessors Rogers, Dr. D. D. Owen and Professor E. Hitchcock, the 
early questioners or opponents of the Taconic system, do not con- 
tain a discourteous word. ‘Their criticisms are such as give life 
and progress to the science. Professor James Hall, whatever 
opinions he may have had or may have orally expressed, has 
nowhere in his notes on the fossils of the Taconic slate (Black 
slate), an offensive remark; and these are all of his writings on 
the subject. Logan, after the (Juebec discoveries of the Canada 
survey, put a few lines in his Canada Report—a very few, in all 
not over twenty; he did it courteously and not even controversi-’ 
ally. He afterward made examinations in Vermont, Massachu- 
setts and New York which gave him confirmatory conclusions, 
but personally he wrote nothing on these conclusions. 
The writer’s acquaintance with the subject began in 1843, after 
an absence abroad of four years; and for many years afterward 
he was learning, but published nothing. After the discoveries of 
fossils in Canada, and the announcements of the Canada Geo- 
logical Survey, I adopted Logan’s opinion; and this is presented 
in my Manual of Geology, published first in 1863. It appeared 
at the time to be the generally accepted opinion. My investiga- 
tions in Berkshire were commenced in July of 1871, in order to 
get at the truth, without any feeling of opposition to Professor 
Emmons. 
Dr. T. Sterry Hunt was one of the strong and active opponents 
of the Taconic system between the years 1849 and 1875. The 
Report of the American Association for 1850 has his decision 
that ‘The results of the [Canada] survey have shown, as I had 
the honor to state at the last annual meeting at Cambridge [in 
1849], that the Green Mountain rocks are nothing else than the 
rocks of the Hudson River Group with the Shawangunk con- 
glomerates, in a metamorphic condition ;” and in his address 
before the same Association for 1871, he stated, as he had done 
many times in the interval, that the conclusion of Rogers and 
