352 A. V/inchell on the Taconic Question. 
embodied the results of later studies both by himself and others, 
and the stratigraphic and palcBontologic grrounds of the system 
were much more fully, accurately and effectively stated. But 
it is only necessary in this examination to learn distinctly what 
was the founder's view in the institution of his sj-stem. 
y. Central conception of the founder of the Taconic sysfejn. 
From a study of the oldest documents treating of the Taconic 
system, it is not difficult to discover their essential purport. 
The central conception of Dr. Emmons was a system of sedi- 
mentary fossiliferous rocks underneath the Champlain group. 
To be a system it must possess distinct stratigraphic limitations 
both above and below, and must contain the records of a system 
of life unlike that of the overlying system. Quite possibly, the 
original propounder had not attained exact views in reference 
to the true limitations of his systems either above or below. 
He entertained the opinion that the Potsdam sandstone was not 
embi^aced in the Taconic; in that he may easily have been 
mistaken. He seems to have entertained the conviction that his 
system extended downward to the crystalline schists, and held 
what he termed "the absolute sedimentary base;" in this he 
may also have been mistaken. The upper and lower limits 
concern, however, only the border land of a great conception 
which with him was entirely original ^ — a vast downward exten- 
sion, below the base of the New York system, of the records 
of inarine sedimentation and of life. 
II. Is THERE A REAL SUB-SlLURIAN SYSTEM? 
1. That the Potsdam sandstone, the base of the New York 
system, does not mark the lowest limit of the record of life, is 
now a fact so notorious as to constitute one of the elementary 
truths of the science. 
2. An extensive fauna of sub-Silurian life has been brought 
to light within the very area over which Dr. Emmons extended 
his system. Many of these forms have been discovered in the 
very strata embraced in the enumeration of the Taconic forma- 
tion. Most of them have been signalized from strata lying on 
the eastern side of lake Champlain, and northward toward 
Quebec — the S wanton slates, the Phillipsburg group, the 
Georgia slates and the St. Albans group — called collectively 
