Current Actio)} in the Ordovicinn. — Hnedemann. 387 
the Saeondaga river and on the west shore of lake Georg'e, as 
well as the direction of the fossils as far north as Nine Mile 
creek, leave no doubt that tlie coast-line of the sea of the 
Utica epoch must have been considerably farther north 
than the present extension of the Utica shale as surface rock 
would indicate. For the shale near Dolgeville, twenty miles 
can be regarded as the minimal distance from the coast- line. 
The measurements of the dip in the Mohawk river valley are 
unreliable on account of several faults in the rocks, they 
would point to an angle of several degrees, which would mean 
an unusual '"steep incline," for an angle of about three de- 
grees gives a descent of one mile in twenty miles, which is a 
comparatively rare occurrence in modern seas. Williams* ob- 
tained some exact figures in central New York. He found 
in Cortland county a descent of fifty-six feet per mile. As the 
dip increases a little towards east, sixty feet per mile can be 
regarded as a minimal value, on account of the greater ap- 
proach of the strata to the coast line in Herkimer count3^ 
These two data, twenty miles distance and a descent of sixty 
feet per mile, however, would give a depth of 1200 for the sea 
in the Mohawk region. It must, therefore, be concluded that 
the depth, in which the Utica shale, showing the arrangement 
of the fossils, has been deposited, was considerable. It agrees 
with this, that the preservation of the delicate rhabdosomes 
of the graptolites points to a very gentle motion of the water, 
which, in most cases did not so much transport the organic 
relics, as arrange them. It is especially this gentle, but <-on- 
stant, deep-reaching action of the moving water, whiclj. to the 
writer, seems not to be quite in accordance with the influence 
to be expected from a tidal current, but rather with that of a 
branch of the general oceanic circulation. The apparent in- 
dependence of the current from the coast, which is indicated 
by the distant transference of mud towards the Ohio river 
and by the approach of the Galena limestone to the coast in 
the northwest, also seems not to indicate the action of a tidal 
current. 
Finally, it is very doubtful, whether a tidal current would 
have been able to influence the fauna of the entire Appalach- 
ian basin in such a degree, as is indicated by the difference 
*Dipin Central New York. Am. J. of Science, vol. 2G, p. 303. 
