CLASSIFICATION OF ROCKS. 
13 
the “ Coal formation” having always been debateable ground ; one class of geologists placing 
it in the Transition, the other in the Secondary class. 
In adopting the new term, an old one is gotten rid of with great advantage. It was odious 
to many, in consequence of its inappropriate meaning as originally applied ; that import being 
disregarded by those who still retain it, considering it in no other point of view than as desig¬ 
nating the class, system or division of rocks which exist between the Primary and the Secon¬ 
dary classes, without any reference whatever to its original meaning. 
In adopting the terms Champlain, Ontario and Erie, there is no intention to make any 
other arrangement than one which, in great part, is purely geographic, the advantage being 
that these names are well known, and that the rocks included under their heads, respectively, 
are, with some exceptions, in force and well characterized along their border. In adopting 
the terms Ontario and Erie, for example, it must be borne in mind that reference alone is 
made to the geology of their southern or New-York border. 
Tabular View of the New-York System in the ascending order. 
New-York 
System. 
\ 
Champlain division. 
Ontario division. 
Helderberg division. 
Erie division. 
Catskill group. 
! Potsdam sandstone, Calciferous group, Black River 
limestone, Trenton limestone, Utica slate, Hudson 
River group. 
( Gray sandstone, Medina sandstone, Oneida conglome- 
\ rate, Clinton group, Niagara group. 
( Onondaga salt group, Water lime group, Pentamerus 
) limestone, Catskill shaly limestone, Oriskany sand- 
J stone, Cauda-galli grit, Schoharie grit, Onondaga 
(. limestone, Corniferous limestone. 
t Marcellus shales, Hamilton group, Tully limestone, 
< Genesee slate, Portage group, Ithaca group, Che- 
v mung group. 
With the above important and convenient arrangement, the whole of the rocks and other 
geological products of the third district will be reduced to a few simple heads, namely, four 
systems and seven divisions, as in the following table : 
1. Primary System,... Requires no further illustration. 
( Embraces the products between the primary 
2. Taconic System,.< and the Potsdam sandstone, which are very 
( partial in the district. 
/ 1. Champlain division. 
\ 2. Ontario division. 
3. New-York System, <3. Helderberg division. 
V 4. Erie division. 
L 5. Catskill division. 
4. Quaternary Systent, { £ 
