308 C. D. Walcott — The Taconic System of Emmons. 



he proposed the Taconic System, with the statement that it 

 was composed of five different rocks, as follows: 



" 1. A coarse granular limestone of various colors which I 

 have denominated Stockbridge limestone" etc. 



" 2. Granular quartz rock, generally fine-grained, in firm, 

 tough, crystalline masses of a brown color, but sometimes white, 

 granular and friable." 



" 3. Slate, which for distinction I have denominated Magnesian 

 slate" etc. 



" 4. Sparry limestone, generally known as the sparry lime- 

 rock." 



" 5. A slate, which I have named Taconic Slate, and which is 

 found at the western base of the Taconic range. It lies adjacent 

 to the Lorraine or Hudson River shales, some varieties of which 

 it resembles," etc. 



A section is given on page 145, fig. 46, to show that the 

 " Taconic System " embraced all the strata between the gneiss 

 on the east and the " shales of the Champlain group " on the 

 west. The latter are represented as unconformably superja- 

 cent to the "Taconic slate." 



His second memoir appeared in 1844* as a pamphlet, pub- 

 lished in advance of vol. i, of the Agriculture of New York, 

 in which, in 1847, the subject matter was reprinted without 

 change. The changes from the stratigraphic scheme of 1842 

 consist in placing the granular quartz at the base of the 

 system, with the Stockbridge limestone conformably resting 

 upon it. A theoretical sectionf is given to show the rela- 

 tion of the various formations. . The crystalline gneiss is rep- 

 resented with (1), the Granular Quartz or brown sandstone 

 resting upon it ; then, in turn (2), the Stockbridge limestone ; 

 (3), Magnesian slate ; (4), Sparry limestone ; (5), Roofing 

 slate ; (6), coarse brecciated bed ; (7), Taconic slate, and (8), 

 Black slate. On the following page, the section shown by 

 fig. 7 represents these beds as all having a high and uni- 

 form dip to the eastward,:}: and with the Hudson river 

 shales (9), unconformably superjacent to the Taconic slate (8). 



When speaking of the lithologic characters of the system, 

 Dr. Emmons says : " Taking one broad view of the whole sys- 

 tem, it may be described as consisting of fine and coarse slates, 



* Agric. N". T., vol. i, pp. 45-112, 1847. The pamphlet of 1844 is very rare,. 

 as few copies were issued, and I shall make all references to its contents as re- 

 printed in the volume of 1847, combining the dates as 1844-47. 



+ Loc. eit. p. 62, fig. 6. 



\ This is corrected for the " Lower Taconic " rocks in the Section published 

 in 1856 (Am. G-eol., vol. i, pt. 2, p. 19). but all the strata of the '; Upper Taconic " 

 are considered superior to the Stockbridge limestone. 



