1887] The Taconic Question Restated. 117 
survey of the State of New York was begun, W. W. Mather was 
charged with the Southern district, including the region east of 
the Hudson, while to Ebenezer Emmons, a pupil of Eaton, was 
given the Northern district, to the west of Lake Champlain; 
Conrad, and after him Lardner Vanuxem, having the Central 
or intermediate district, including the counties of Oswego, Oneida, 
Herkimer, and Montgomery, and extending southeastward along 
the valley of the Mohawk to the Southern district. 
Along the base of the Adirondacks, Emmons now found, in 
some parts, between the Transition Lime-rock of Eaton and the 
underlying Primitive crystalline schists, a granular or compact 
quartzite, which he called the Potsdam sandstone. For the rest, 
he did no more than confirm the determinations of his master, 
retaining the Birdseye or Encrinal Lime-rock of the latter as a 
subdivision of the Metalliferous Lime-rock, to the upper and 
lower portions of which he gave the names of Trenton and 
Chazy ; while in the succeeding Second Graywacke he recognized 
as subdivisions, the Utica slate, the Loraine shale, the Gray or 
Oneida, and the Red or Medina sandstone, all of which, with the 
inclusion of the Potsdam sandstone, he called the Champlain 
_ division of the New York system. The last two members of 
this were, however, subsequently joined to what was called the 
Ontario division of the same system. 
§6. The metamorphic hypothesis was then in fashion with some 
American geologists, and had already been applied by Nuttall, as 
early as 1822, to the rocks of Southeastern New York, the 
gneisses and crystalline limestones of which he supposed to have 
been formed by a subsequent alteration of portions of the adja- 
cent graywacke and fossiliferous limestones. Mather, in exten- 
sion of this notion, conjectured that the Primitive Quartz-rock, 
the Primitive Lime-rock, and the Transition Argillite of Eaton 
might, in like manner, be the results of an alteration of the mem- 
bers of the Champlain division of Emmons, excluding the upper 
sandstones ; and in his final Report in 1843, on the Geology of the 
Southern district of New York, further maintained that not only 
the divisions of Eaton just mentioned, but the crystalline rocks 
in that State lying to the south and east of the Highland range, 
comprising Westchester and New York Counties, and embracing 
Manhattan Island, like the similar rocks of western New Eng- 
land, were “nothing more than the rocks of the Champlain. d di- 
