454 ADDRESS OF T.:STERRY HUNT. 
founders of American geology, at least as early as 1832, distin- 
guished in his Geological Text book (2d edition) between the gneiss 
of the Adirondacks and that of the Green Mountains. Adopting 
the then received divisions of primary, transition, secondary and 
tertiary rocks, he divided each of these series into three classes, 
which he named carboniferous, quartzose and calcareous ; meaning 
by the first schistose or argillaceous strata such as, according to 
him, might include carbonaceous matter. These three divisions in 
fact corresponded to clay, sand, and lime-rocks, and were supposed 
by him to be repeated in the same order in each series. This was 
apparently the first recognition of that law of cycles in sedimenta- 
tion upon which I afterwards insisted in 1863.* Without, so far as I 
am aware, defining the relations of the Adirondacks, he referred to 
the lowest or carboniferous division of the primary series, the crys- 
talline schists of the Green Mountains, while the quartzites and 
marbles at their western base were made the quartzose and calca- 
reous divisions of this primary series. The argillites and sandstones 
lying still farther westward, but to the east of the Hudson River, 
were regarded as the first and second divisions of the transition 
series, and were followed by its calcareous division, which seems to 
have included the limestones of the Trenton group ; all of these 
rocks being supposed to dip to the westward, and away from the 
central axis of the Green Mountains. Eaton does not appeal 
to have studied the White Mountains, or to have considered their 
geological relations. They were, however, clearly distinguished 
from the former by C. T. Jackson in 1844, when, in his report on 
the geology of New Hampshire, he described the White Moun- 
tains as an axis of primary granite, gneiss and mica-schist, Over- 
laid successively, both to the east and west, by what were design® 
ted by him Cambrian and Silurian rocks ; these names having; since 
the time of Eaton’s publication, been introduced by English geol- 
ists. While these overlying rocks in Maine were unaltered, he 
conceived that the corresponding strata in Vermont, on the western 
side of the granitic axis, had been changed by the action of intrusive 
serpentines and intrusive quartzites, which had altered the Cam- 
brian into the Green Mountain gneiss, and converted a portion of 
the fossiliferous Silurian limestones of the Champlain valley int? 
white marbles.+ Jackson did not institute any comparison P 
* Amer. Jour. Sci., II, xxxv, 166. 
t Geology of New Hampshire, 160-162. 
