1887] The Taconic Question Restated. 115 
rock, by which names he designated the quartzite and the crys- 
talline limestone of the Taconic (or Taghkonic) Hills in western 
New England. 
§ 2. Above the Primitive, Eaton placed the Transition series, in- 
cluding, like the last, three divisions: First, at the base, a schistose 
or so-called argillaceous member, named by him the Transition 
Argillite, and representing in this second series the gneisses and 
crystalline schists of the Primitive. Second, a silicious member, 
consisting of a great group chiefly of sandstones and conglomer- 
ates, comprehensively described by him as millstone-grit, rubble, 
and graywacke-slate, the whole representing in the Transition 
series the Quartz-rock of the Primitive, and called the First 
Graywacke or Transition Graywacke, a term borrowed from 
German geologists. Third, a limestone named by him the Sparry 
Lime-rock, and representing in this series the Granular Lime- 
rock of the Primitive. Eaton insisted upon the existence of a 
' stratigraphical break, and a discordance, between the Transition 
Argillite and the overlying Transition Graywacke, the distribu- 
tion of which latter was described in detail. It was said to be 
“seen resting on the Argillite in Rensselaer County, where its 
subdivisions form a ridge which extends from Canada through 
the State of Vermont, and Washington, Rensselaer, and Columbia 
Counties in New York.” The conglomerates of this Transition 
Graywacke were further said to make “the highest ridges between 
the Massachusetts line and the Hudson.” 
§ 3. To the west of Lake Champlain, along the base of the Ma- 
comb Mountains (since called the Adirondacks), and resting upon 
the Primitive gneiss, Eaton found what he called the Calciferous 
Sand-rock (a magnesian limestone, sometimes holding gypsum), 
which he declared to be the equivalent, in this region, of the Sparry 
Lime-rock, and to constitute, with its overlying Metalliferous 
Lime-rock (a term borrowed from Bakewell), the third or cal- 
careous division of the Transition series. The sandstone since 
known as the Potsdam, which is often wanting at the base of the 
fossiliferous limestones in this region, was apparently unknown to | 
him. It is here to be noted that Eaton, unlike many of his suc- 
cessors, did not confound these limestones, nor their stratigraphi- 
cal equivalent to the east of the Hudson—the Sparry Lime-rock 
—with the crystalline limestone of. Western Massachusetts, but 
recognized the fact that this, the Primitive Lime-rock, together 
