12 
GEOLOGY OF THE THIRD DISTRICT. 
16. Pentamerus limestone. 
17. Catskill or Delthyris shaly limestone. 
18. Oriskany sandstone. 
19. Cauda-galli grit. 
20. Schoharie grit. 
21. Onondaga limestone. 
22. Corniferous and Seneca limestone. • 
23. Marcellus shales. 
24. Hamilton group. 
25. Tully limestone. 
26. Genesee slate. 
27. Portage or Nunda group. 
28. Ithaca group. 
29. Chemung group. 
30. Catskill group, or old redsandstone. 
Finally the products which belong to the Post-tertiary age, which are here placed together 
under the head of Quaternary System, in order to avoid interference with arrangements else¬ 
where made. They form two divisions. The first consists of clay, sand, rolled stones, boul¬ 
ders and other blocks of transport, being all transported materials. The second division con¬ 
sists of lake marl, calcareous tufa, bog ore, peat or muck, soil and mineral springs ; being pro¬ 
ducts of the places where existing or discovered, excepting soil in part, being of tw'ofold origin. 
In commencing this report, I had no intention to make any arrangement of the rocks of the 
district from the Potsdam sandstone to the Catskill group, but a geographical one merely of 
the district, and in accordance with the strikingly peculiar features of that highly interesting 
portion of the State, intending also to content myself with a numerical distinction of the parts, 
and even to retain the term Transition Class, as heretofore used for that series, waiting for 
the fossil character of the whole State before entering upon the subject. Finding, however, 
that the geologist of the second district had adopted the term New-York Transition for the 
same series, but leaving out its upper member the Catskill group or old redsandstone ; 
adopting also the well known names of Champlain, Ontario and Erie for some of the divi¬ 
sions of the class, the intention mentioned was abandoned, and the views of Dr. Emmons 
were cordially embraced and adopted with some modifications. 
In this report the term New-Yoi'k System will be used, and will include all from the Pots¬ 
dam sandstone, inclusive, to the “ Coal formation.” As no part of the latter deposit exists 
in the State, with the exception of a few partial outliers or detached masses in the fourth 
district, consisting of conglomerate, which forms the lower part of the mass, the whole series 
in New-York being complete as far as the beginning of the coal era, the system has for its 
designation a name which geographically is perfect, leaving nothing more upon the subject to 
be desired. 
The Nevj-York System, by this arrangement, includes all the undisputed transition rocks. 
