116 = The Taconic Question Restated. [Feb. 
with the Primitive Quartz-rock and the Transition Argillite, and 
the great Transition Graywacke, were all alike wanting in the 
Adirondack region between the gneisses, constituting the lowest 
member of the Primitive, and the fossiliferous limestones, the 
highest member of the Transition series. 
§ 4. Above this last he recognized a third, or Lower Secondary 
series, having, like the others, for its inferior member an Argillite 
or Graywacke-slate, and for its second or silicious member a 
sandstone and conglomerate. These two members were by 
Eaton united under the name of the Second Graywacke, which 
he declared to be lithologically very much like the First or 
Transition Graywacke, but distinguishable therefrom by the fact 
that it is above instead of below the Transition limestones, and 
is, moreover, overlaid, in its turn, by the Lower Secondary lime- 
stones. These comprised the Geodiferous Lime-rock and the 
Corniferous or Cherty Lime-rock, with its included layers of what 
he called “stratified horn-rock,’ in which two subdivisions we 
at once recognize the Niagara and Upper Helderberg limestones 
of James Hall. In each of these triple series Eaton recognized, 
in ascending order, an argillaceous or schistose, a silicious, and 
a calcareous member. 
All of the above details of his classification may be gathered 
from Eaton’s “ Geological and Agricultural Survey of the Erie 
Canal” (1824), and in the second edition of his “ Geological Text- 
book” (1832). They were set forth by the present writer, in 
1878, in his volume on Azoic Rocks (“ Report E of Second Geo- 
logical Survey of Pennsylvania”); and more fully, with a tabular 
view, in an essay on “The Taconic Question,” in the first and 
second volumes of the “Transactions of the Royal Society of 
Canada,” in 1883 and 1884, which is reprinted, with considerable 
additions, in his “ Mineral Physiology and Physiography” (pages _ 
` §17-686) in 1886. The student who follows the painful history 
of the half-century of controversy which has been required to 
bring order out of the confusion in which his immediate suc- 
- cessors involved this great problem of American geognosy, can 
_. only regard with reverence the wonderful insight by which Amos 
3 sche was enabled, at this early period, to comprehend the com- 
_ plex stratigraphy of the Hudson and Champlain valleys and the 
: = T When, sre later, in 1837, a systematic geological 
