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



terrane (2) in the section but on the map they are merged with 

 the Georgia terrane (5). 



The exact localities of fossils within the typical Taconic area 

 are shown by the letter F. Many localities to the north and 

 south are not indicated. 



Section. — The geologic section crosses the Taconic area on 

 the line marked A, B, on the map, which is very near the line 

 of the original section published by Dr. Emmons in 1847 

 (Geol. 1ST. Y., pt. 1, pi. xviii, Sec. 1). On the line C, D fossils 

 have been found more abundantly on the eastern side, and the 

 structure is found as in Dr. Emmons's section of 1856. 



1. Cambrian quartzite — Terrane No. 1. 



2. Hydromica (Potsdam ?) shales — Terrane No. 2. 



3. Trenton, Chazy and other limestones of the Lower Silurian 



— Terrane No. 3. 



4. Hudson (hydromica) shales of the Taconic range and, in the 



Hudson valley, the Hudson terrane — Terrane No. 4. 

 4«. A belt of strata of the Hudson terrane, faulted in between 

 Cambrian rocks — Terrane No. 6 of text. 



5. ha. Slates, with interbeclded limestones and sandstones of 



the Georgia Terrane, of the Cambrian — Terrane No. 5. 



6. Pre-Cambrian (Agnotozoic) or Archean rocks, a, b, c, d, 



fault lines, known to the writer, in Washington County, 

 N. Y. The hade of the Ball Mountain fault (a) is ap- 

 proximately correct (see fig. 12) while that of the other 

 faults is probably much more oblique or inclined to hori- 

 zontal than as represented. They are drawn to show where 

 they occur and not to indicate the hade or angle of the 

 faults. The minor undulations, faults and displacements 

 that occur on the east side, between 3 and the gneiss ai'e 

 not represented. , 



Comparing this with Dr. Emmons's sections, we find a dif- 

 ference in the arrangement of the strata in the eastern half. 

 The " Lower Taconic " embraced the strata from Terrane No. 

 1, on the east, to Terrane No. 3, on the west side of the Ta- 

 conic range, and included all the strata of the original " Taconic 

 System " as known and defined by Dr. Emmons in 1842. The 

 " Upper Taconic " included the strata of terranes Nos. 2, 4, 

 4#, 5, and 5a, west of the Taconic Range, which was added to 

 the original " Taconic System " in 1844. 



I have not attempted to show that the quartzite contains 

 interbedded limestones and schists in some localities, nor that 

 the limestone series (3) is broken by interbedded schists or are- 

 naceous beds ; nor that, as at Graylock, the quartzite (1) ex- 

 tends completely beneath the synclinal of the limestone (3) and 

 appears on the western side. It is only the illustration of the 



