102 
GEOLOGY OF THE SECOND DISTRICT, 
in the grouping proposed; while it leaves us at leisure to subdivide, if necessary, and study 
the several groups as minutely as we please, or as the nature of the formations require. 
CHAMPLAIN GROUP. 
Some of its most important characters. — The order of succession, or the superposition of 
the members composing it. 
Returning now to the consideration of the members of the Champlain group, I shall pre¬ 
sent, in the first place, a section giving the names and the order of succession of the rocks 
composing it. 
Primitine. Champlain Group, nr Lower Transition Rocks. 
*• 
3. 4. 5. . 6. 7. 
8. 9. 10. 
1 . 
Primai-y ; 
5 Chazy limestone; 
9. Lorrnin shales; 
2. 
Oxides of iron ; 
6. Birdseye limestone; 
10. Grey sandstone ; 
3. 
Potsdam sandstone ; 
7. Trenton limestone ; 
11. Medina sandstone. 
4. 
Calciferous sandrock; 
8. Utica slate; 
1. Potsdam Sandstone. 
Disturbances. — Fossils .— The base of the Transition System. — Diversity of materials. 
The base of the Transition system of New'-York is the Potsdam sandstone. Its lowest 
portion is a granitic conglomerate, in which large masses of quartz, the size of a peck mea¬ 
sure, are often enveloped: they are rounded and. w'ater-worn, and held together merely by a 
finer variety of the same materials. The part which is properly a standstone, presents Some 
variety of aspect and texture at the different places where it appears but there are two prin¬ 
cipal varieties, which it may be well to notice: 1 st, an even-bedded and somewhat porous 
rock, at many places a distinct white friable sandstone ; in others, it is a yellowish brown 
sandstone, the particles of which are compacted together, so as to form a firm even-grained 
mass. The rock at the Potsdam quarry furnishes a good variety of the latter ; those of 
Bangor and Moore, of the former. 2d, a close-grained, sharp-edged mass, with natural joints 
traversing it in- two principal directions, so as to divide it into acute rhomboids, so closely, 
wedged together that it is with difficulty quarried. It is, in fact, a hard quartz rock, scarcely 
passing for a sandstone. Keeseville, Whitehall and Port Kent furnish examples of this 
