994 The Crystalline Rocks of the Northwest. (October, 
` fectly understood the extent and importance of his discovery, and 
he may have incorrectly described its range and scope, but none 
of these faults, nor all of them, should deprive him of the credit 
of having made the discovery. He did more, he defended it to 
the last day of his life, and averred that “the Taconic system 
stands out as boldly as the Carboniferous.”! The argument 
against the Taconic system which appeals to imperfect or incor- 
rect definition by its author, will apply with equal force against 
the Silurian system and also against the Cambrian; also against 
the Huronian and the Laurentian, and perhaps with still greater 
force against the Hudson River, since none of these were correctly 
and properly defined at first by their authors. 
If the equities of geological nomenclature, in the light of the 
results of later researches, demand of geologists of this genera- 
tion a fair consideration of the claims of Dr. Emmons, that com 
sideration must be granted. No amount of error, though heaped 
to the sky and supported by the highest authority, can long sub- 
sist. The truth, though tardy in asserting itself, will finally throw 
off the burdens under which it labors, and will shine the brighter 
for the darkness which preceded it. 
If we examine the descriptions, given by Dr. Emmons, of his 
Taconic system, we shall find that he makes the following broad 
stratigraphic distinctions. 
I. His highest member’is what he designates d/ack slate, ges | 
he declares, in some cases, plunges apparently beneath the at- 
cient gneisses” and contains a considerable amount of carbon 
aceous matter. In this slate, at Bald mountain, were found two 
genera of primordial trilobites that were described by Dr. Em- 
mons, the much buffeted Avops trilineatus? and Elliptocephala or 
phoides. 
II. Under the black slate his next grand distinction wa e 
so-called Taconic slate, which he described as argillaceous, 
iceous and “ talcose,” the upper part being suitable for roo) ; 
and other portions adapted for flagging. It is gre 
grayish and sometimes of a chocolate color. Its grain Nes 
fine, but in some places it is arenaceous rather than ar gillaceous 
Thickness about 2000 feet, 
* Letter to Jules Marcou, dated Raleigh, N. C., Nov. 6, 1860. 
* According to Mr, Ford this is Conochoryphe. 
