A. Wincheil on the Taconic Question. 351 
distinction. As expressed in the agricultural report, " The 
members of the Taconic system have a different arrangement. 
The sandstones, limestones and slates are not only different in 
their relative position but they are much thicker than those w^ith 
which they have deen supposed to be identical in the New York 
system." ' 
Compared with the primary rocks they are less crystalline, 
and in constitution, the rocks themselves differ, and also inclose 
a different range of accessory minerals. Actinolite, epidote, 
titanic and auriferous sulphuret of iron and graphite are confined 
to the primary. Further, the minerals of the Primary have a 
uniform connection with the rock masses; they are contempo- 
raneous with them. There are rarely any cavities around them j 
but they are closely invested on all sides by the materials of 
which the rock is composed. On the contrary, in aqueous rocks, 
minerals occur in pre-existing cavities, and they are usually 
composed of substances more or less soluble under one or more 
conditions.^ 
(2). Stratigraphic unconformities: These appear not to 
have been distinctly brought out before 1S46. In the agricul- 
tural report, page 56, three sections are delineated, in which 
the Calciferous sandstone is shown to overlie the Taconic strata 
unconformably. In plate XVIII, six sections are given in de- 
tail, showing the unconformable relations of the Taconic and 
New York systems. The details of the report point out 
marked unconformities with the underlying Primary masses.* 
(3). Palieontologic unconformity: In the first enunciation, 
the Taconic beds were supposed differentiated from the New 
York system by their complete destitution of organic i-emains. 
At the date of the agricultural report, Dr. Emmons' view on 
this point was embodied in the following conclusion: "The 
Nereites and other fossils of the Taconic slates are unknown in 
any of the members of the Champlain group; the mollusca of 
the New York system are also wanting." * 
In subsequent publications, the author of the Taconic system 
1 Report on Agriculture, p. 168. 
2 Report on the Second District, pp. 138-141. 
^ See, for instance, p. iii. 
* Agricultural Report, p. loS. 
