242 THE CAMBRIAN. Ibull.81. 



Dr. Henry Hicks 1 says of it : 



The Treniadoc group, therefore, may be said through many of its types of fossils to 

 link the Cambrian and the overlying Ordovician (Lower Silurian) formations to- 

 gether, while it yet marks very distinctly the horizon in which all the truly charac- 

 teristic types in the Primordial faunas are lost. 



TACONIC. 



The first proposition to apply the name Taconic to a system or series 

 of rocks is found in a gazetteer of the State of New York, published in 

 1842. 2 The article is unsigned, but it bears internal evidence of having 

 been written by Dr. Ebenezer Emmons as his first presentation of the 

 views which were more fully elaborated and published later in the same 

 year. He describes the Taghkauic range, and states that the rocks 

 composing the same are situated between the gneiss of Hoosic Moun- 

 tain on the east and the slates of the transition on the west; that they 

 bear a very close resemblance to the primary on the east, and, on the 

 other hand, a great similarity to the transition slates on the west. 3 



He says : 



It is not proposed in this plan to separate these rocks from the primary, but to 

 consider them as belonging to the upper portion and to speak of them as the Tagh- 

 kauic rocks, or perhaps as the Taghkanic system. * * * Considering them for the 

 present as belonging to the upper portion of the primary, the Taghkanic rocks will 

 be composed, first, of a peculiar talcose slate, or a magnesian slate in part ; in 

 other parts it is plumbaginous, which strongly soils the fingers. * * * Second, oi 

 white, gray, and clouded limestone varying in texture from fine to coarse granular, 

 often iuterlamiuated with slate, the latter often merely coloring the limestone so as 

 to impart the clouded appearance. * * * Third, of granular quartz, or a sandstone 

 generally siliceous and of a brown color. 4 



In the concluding remarks on the Taghkanic system, we read : 



On tho whole, in regard to those rocks we have denominated "Taghkanic," we be- 

 lieve they ought to be separated from those on the east, being, as a whole, clearly 

 distinct from them. 5 



A second memoir appeared in 1842, in which the term "Taghkanic n is 

 changed to Taconic, aud a detailed description given of the geographic 

 distribution and character of tbe rocks forming the Taconic system. 

 A typical section is presented with the following comment: 6 



The following section, extending from Petersburgh, Rensselaer County, to Adams, 

 Massachusetts, embraces all the rocks in this system. Its direction is nearly east 

 and west, or perpendicular to the strike of the system over which it passes. 



1 On borao recent researches among Lower Paleozoic rocks in the British Islands. Proc. of the 

 Geologists' Association, vol. 7, p. 9. 



2 Topography. geology, and mineral resources of the State of New York. Gazetteer of the State of 

 New York, by James Disturnell. Albany, 1842, pp. 5-25. 



3 Op.cit.,p. 11. 



4 Op. cit., p. 11. 



8 Op. cit.,p.l2. 



6 Geology of New York, part 2, comprising the survey of the 2d geological (northern) district, 1842, 

 p. 145. 



