Miller on the Taconic. 237 
ess, Columbia, Rensselaer and Washington counties, and, passing north, 
strikes the west line of Arlington, Vermont. 
5. Taconic slate, with its subordinate beds of roofing slate and coarse 
brecciated layers. It occupies almost the whole of Columbia, Renssel- 
aer and Washington counties, and extends to the base of the Taconic 
range, which separates New York from Vermont and Massachusetts, 
and has an immense thickness. It crosses the Hudson above Newburg, 
and passes through Orange county into New Jersey. From the roofing 
slate he defined Diflograft us stmflex, and from the Taconic slate in 
Washington county Buthotrefhis Jlexuosa, B. rigida, PaUeocliorda marina, 
Nema^podia tenuissivia, Nereitcs devjeyi, JV. gracilis, N. jacksoni, N. lanceo- 
latus, JV. lootnisi, N. pugnus, Myrianites murchisoni and M. sillitnani. 
6. Black slate, forming so far as he knew the highest meinber of the 
Taconic system, and from which he named and illustrated Elliftocepha- 
lus asapJioides and Atops trilineatus. 
He identified the Smithfield limestone in Rhode Island with 
the Stockbridge limestone, and an accompanying slate with the 
Magnesian slate; and in Blackstone valley he found the brown 
sandstone and fine granular quartz. He recognized in the 
slates in Waterville, Maine, the Taconic slate of New York, 
and found the Nereitcs^ at Kennebec. The fine roofing slates 
on the Piscataqua he found subordinate to the Taconic slate in 
like manner as they exist in New York. And, jointly with 
Douglass Houghton, the Taconic system was found largely de- 
veloped in the upper peninsula of Michigan ; the slates of the 
formation with their fucoidal impressions and the granular 
quartz were both recognized. In 1846 he reproduced his work 
on the Taconic system in a report on the Agriculture of New 
York, with an appendix describing a conglomerate at the 
base resting unconformably upon granitic rocks. 
In this manner this geological subdivision was first deter- 
mined, defined and established, and it should have been recog- 
nized from that time forward. But others, much less in- 
formed, disputed the existence of the rocks, erroneously refer- 
red his fossils to more recent genera, and some, finding the 
same rocks, gave to them different names, which added to the 
confusion, and seriously retarded the progress of knowledge re- 
specting them. It may be that later researches have not, in 
every respect, sustained his determinations, but Ford's work 
near Albany, New York, where the position taken by Emmons 
was most violently assaulted, has not only corroborated him, 
