118 
GEOLOGV 
This series of strata in the third district, is a more complete classification of the sedimentary Tran- 
sition rocks than had until that time been made. 
Hall gives, pages 453, 454, and 455, a table showing the series of rocks in the fourth district, 
hut as this table is almost wholly a reproduction of those previously published by Vanuxem and 
Conrad, it is needless to repeat it here. 
By comparing their observations, the geologists and the paleontologist for the State of New 
York agreed upon the following series for the final classification of the Paleozoic strata of New York, 
which was published in the FINAL REPORT, edition in 4°; Albany, 1842. 
II. laconic system. 
III. New York system. 
1. 
Potsdam sandstone. 
2. 
Calciferous sandrock. 
3. 
Black river limestone group. 
4. 
Trenton limestone. 
5. 
Utica slate. 
6. 
Hudson river group. 
7. 
Gray sandstone. 
8. 
Oneida Conglomerate. 
9. 
Medina sandstone. 
10. 
Clinton group. 
11. 
Niagara group. 
12. 
Onondaga salt group. 
13. 
Water lime group. 
14. 
Pentamerus limestone. 
15. 
Delthyris shaly limestone. 
16. 
Encrinal limestone. 
17. 
Upper Pentamerus limestone. 
18. 
Oriskany sandstone. 
19. 
Cunda-Galli grit. 
20. 
Schoharie grit. 
21. 
Onondaga limestone. 
22. 
Corniferous limestone. 
23. 
Marcellus slate. 
24. 
Hamilton group. 
25. 
Tally limestone. 
26. 
Genesee slate. 
27. 
Portage group. 
28. 
Chemung group. 
svstoin 
or Old Ked Sandstone. 
De Verneuil’s Synchronism.) 
Lower Silurian. 
Upper Silurian. 
Devonian formation. 
IV. Old 
V. Conglornerato of the Carboniferous system. 
This classification is certainly a very remarkable work, and although the strata are very re- 
gular and almost horizontal, much labor and research was required in order to group them, and 
to recognize their respective positions. More detailed study will probably modify certain parts of 
this series, hut without changing its meaning or general results. 
I have entered somewhat fully into the history of this classification of the Paleozoic rocks of 
the State of New York, chiefly on account of its importance, since by its means the Transition 
