256 
GEOLOGY OF THE FOURTH DISTRICT. 
Feet. Inches. 
1. Sandstone, becoming shale farther south_ 6 0 
2. Concretionary strata of shale and sandstone_ 5 0 
3. Sandstone _ 1 0 
4. Shale, olive or brownish, and fissile_ 5 0 
5. Sandstone _ 1 0 
C. Shale similar to No. 4_ 6 0 
7. Thin stratum of sandstone. 
8. Shale_ 4 0 
9. Greyish olive sandstone 6 to 20 inches thick, running out and again re¬ 
appearing. 
10. Shale.. 4 0 
11. Brownish olive sandstone_ 3 0 
12. Shale, olive and greenish_ 2 0 
13. Sandstone and interlaminated shale_ 2 0 
14. Shale.. 7 0 
15. Sandstone in thin layers_ 3 0 
16. Shale_ 7 6 
17. Sandstone in thin layers_ 5 6 
18. Shale_ 3 0 
19. Sandstone in thin layers___ 2 0 
20. Shale..-... 2 0 
The fossils at this place are Cypricardia, Avicula spinigera, Delthyris, Orthis -, 
large numbers of Orthis unguiculus, Orhicula, Loxonema, Tentaculites, Sec. Scarcely a 
fossil is common to the two localities, though the lithological character is in a great degree 
similar. Both the shales and sandstones are more deeply colored than at Chemung Narrows. 
These sections are given from points where every inch can be measured, and consequently 
there is no error respecting thickness or character ; and as the whole is seen in connection, 
there is no repetition of the same strata. At other places similar sections show some variation 
from these in lithological characters, and also a considerable difference in the species of fossils 
which the strata contain. We often find, in an exposed cliff of a few hundred feet extent, that 
several of the sandy strata thin out, sometimes reappearing, though often not again seen. 
Such changes on a small scale are the same which the whole group undergoes in its western 
extension, the evidences of which are already given. 
Diagonal lamination, and structure of strata. — The shaly strata of this group appear 
to have been quietly deposited in the bed of the ocean, as we should naturally suppose of a 
mass having its origin eastward. The sandy strata are constantly diminishing and disappearing, 
and they present various interesting phenomena of diagonal deposition, interlamination, and 
intermixture of shaly matter. The sand has evidently often been deposited at intervals, being 
pushed along over the bottom covering a previously inclined surface; and this has been fre¬ 
quently repeated. This character becomes more marked towards the west, where nearly all 
