298 The American GeoUxjist. May, 1895 
found them greatly changed, broken and involved with cer- 
tain eruptives. It matters not that he considered, at that 
time, that the sedimentary strata which he had been studying 
were of the age of the Trenton and Hudson River (Lower Si- 
lurian), for he distinctly aliirmed that they were geograph- 
ically continuous from Rutland, Vermont, to New York city. 
The particular strata here referred to are the Stockbridge 
limestone and its associated schists, and the granular quartz, 
and also the Georgia or magnesian slates of the Taconic 
Mountain range.* It is sufficient to say that these several 
parts of the original Taconic of Dr. Emmons have since then 
been shown to be of Lower Cambrian age, bj'' the discovery of 
characteristic fossils by officers of the United States Geologi- 
cal Survey, at many places in Vermont and eastern New York.f 
These sedimentary rocks, bearing their acquired crystalline 
petrographic characters, continue further southwest, entering 
New Jersey. They are also affected by a similar intrusion of 
eruptive rock at Rosetown, N. Y. In New Jersey they have 
afforded 01enellus,+ and at Rosetown the eruptives are con- 
sidered by J. F. Kemp§ as " later than tlie Tompkins Cove 
limestone," whose Cambrian age " seems to be increasingly 
probable." It should be remembered that until these discov- 
eries were made these sedimentary rocks, whose texture is 
sub-crystalline and crystalline, and wliich consist of gneiss, 
quartzyte, mica schist, marble and magnetite iron ore, had 
been believed to be Archean, and had been so mapped gener- 
ally. They differ, however, from the true Archean. They 
extend into the Adirondacks, westwardly from the Vermont 
area, carrying their characteristic structural and petrographic 
features. One of their most noticeable strata is the white 
marble. This is extensively wrought in Vermont and on the 
northern slopes of the Adirondacks. as well as in New Jersey. 
That there are two crystalline series in the Adirondacks has 
long been known, although in default of careful study the 
*Ani. Jour. Sci., many papers from 1880 to 1887. 
fWALCOTT, Hulletin 30, U. S. Geol. Sur.: J. E. Wolff, Bull. Geol. Soc. 
Am., vol. IT, 1891, pp. .S31-337; T. Nklson Dale, }3uI1. Geol. Soc. Am., 
vol. HI, p. 514, 1892. 
:t:F. L. Nason, Geol. Sur. of New Jersey, for 1890. The posl-Archeau 
age of the white limestones of Susse.v Co. 
§Am. Jour. Sci., (3), xxxvi, pp. 247-2.53, 1888. 
