218 DR. THOMAS STERRY HUNT ON THE 
à 
of the Erie Canal, published in 1824, I have elsewhere endeavored to frame a connected 
statement of these views,* which is here briefly resumed. 
§ 2. Dividing the stratified rocks of north-eastern America into five great groups, 
namely: I. Primitive; IH. Transition; III. Lower Secondary ; IV. Upper Secondary; V. 
Tertiary; Eaton supposed that each of these groups “commenced with carboniferous 
slate and terminated with calcareous rocks, having a middle formation, the centre of which 
is quartzose.” This three-fold division and alternation in each great series, which Eaton 
regarded as universal, was, so far as I know, the first recognition of the principle, now so 
generally understood, of cycles in sedimentation. 
§ 3. These three divisions evidently correspond to argillites, sandstones and lime- 
stones, but in the application of his scheme its author allowed himself considerable liberty 
of interpretation, and referred to his first or argillaceous division, not only clay-slates, but 
the great body of crystalline schists. In this way, the first division of the Primitive series 
was made to embrace both the gneisses of the Adirondacks and the Highlands of the 
Hudson, and tke unlike crystalline rocks of New England; including, besides gneisses, 
various hornblendie, chloritic and micaceous schists, in some of which strata the occur- 
rence of graphite was held to justify the title of carboniferous, applied to these rocks as a 
whole. Following this first division of the Primitive series, (I. 1) Eaton recognized in 
western New England the second or silicious division, (I. 2) and the third or calcareous 
division, (I. 3) represented respectively by the Granular Quartz-rock and the Granular 
Lime-rock or marble of the Taconic range. 
§ 4. Succeeding these, came the rocks of his second or Transition series. Of this, the 
first or carboniferous division was the Transition Argillite, (II. 1) which in many localities 
directly overlies the Primitive Lime-rock, and consists in part of roofing-slates, with 
coarser and more silicious layers, and in part of soft unctuous micaceous schists. To this 
Transition Argillite succeeds, according to Eaton, the First Graywacke or Transition Gray- 
wacke, representing the second or silicious division of the Transition series, (II. 2) and 
consisting of the so-called gray wacke-slate, with sandstones and conglomerates. The base 
of the First Graywacke was declared to rest unconformably upon the Transition Argillite. 
§ 5. The geographical distribution of the First Graywacke—a very important point 
was carefully indicated by Eaton. “It is seen resting on the 


in our present inquiry 
Argillite, near Col. Worthington’s on the Little Hoosic, near the eastern limit of Renssel- 
laer county. On ascending the western hill or ridge, the graywacke-slate, rubble and 
millstone-grit [elsewhere indicated by Eaton as making-up the First Graywacke] are found 
in succession. This ridge extends from Canada, through the state of Vermont and Wash- 
ington, Renssellaer and Columbia counties in New York.” Elsewhere, we are told by 
Eaton that the rubble or conglomerate of this First Graywacke “ forms the highest ridges 
between the Massachusetts-line and the Hudson.” He also supposed that the Shawan- 
gunk Mountain of Ulster and Orange counties, on the west side of the Hudson, now 
referred by New York geologists to the horizon of the Second Graywacke, “is a continua- 
tion of the grit and rubble of the First Graywacke of Renssellaer county.” + 
§ 6. To the third or calcareous division of the Transition series (II. 3) was referred by 


* Azoic Rocks, ete., page 24-29 ; being Report E, of the Second Geological Survey of Pennsylvania, 1878, pp. 253. 
+ Geological Textbook, 2nd Ed. pp. 74, 93, 123. 

