1884.] The Crystalline Rocks of the Northwest. 993 
stead of destroying the Taconic system, are only confirmatory of 
the published statements of Dr. Emmons in 1846. 
Although the existence of the Taconic in Maine and Rhode 
Island, as claimed by Dr. Emmons, may not be maintained by 
further research, it is certain that he had the approval of Dr. 
Douglas Houghton in extending it into the State of Michigan. 
In later years, he also traced these rocks through Pennsylvania 
and Virginia into North Carolina. In Michigan his identifica- 
tions have since been set aside and the same rocks have been de- 
nominated Huronian by Brooks, Wright, Irving and others. In 
North Carolina Mr. Kerr has, in the same way, substituted the 
name Huronian. The conclusive fact that these slates had been 
seen, by Dr. Houghton, in many localities, to pass beneath the 
Potsdam sandstone, was considered ample to supply the only im- 
portant point of evidence lacking in the Hudson valley. Dr. 
Emmons closes his discussion by stating his theme thus, referring 
to the facts obtained from Dr. Houghton: “ It would be difficult 
to add to the weight of this testimony in regard to the separate 
and independent existence of a system of fossiliferous rocks, of 
an age anterior to the Silurian or New York system.” 
It is not necessary to refer to the controversies that arose 
from the creation of the imaginary Quebec group, nor to char- 
acterize in deserved terms the attempt to bury the Taconic 
in the Quebec coffin. It is not necessary to quote the sup- 
Port which Emmons had from Barrande, nor to recount the 
discoveries of Mr, Ford nor the observations of Brooks in St. 
Wrence county, N. Y., and Rogers in Pennsylvania, though 
these last both affirm that beneath the Potsdam sandstone are 
extensive beds of semi-crystalline strata.! 
ere may be reasons why the current literature of American 
Stology is almost silent respecting the great work of Emmons, 
and why the Taconic is not known among the recognized geolog- 
ical formations ; but we have nothing to do with these at this 
time. We have now only to say that it seems necessary to admit 
that when Dr. Emmons insisted on a great group of strata be- 
longing to the age of the Lower Cambrian, lying below the Pots- 
dam sandrock in New York, he had some foundation more sub- 
stantial than imagination or mere hypothesis. He may have 
chosen an unfortunate designation. He may have but imper- 
"Address of H, D. Rogers, 1844, hefore the Assoc. Amer. Geol. and Nat. 
