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frequently mingled. This, Dr. Newberry said, illustrated 
the truth of a view held since many years by himself, that 
the accumulation of sedimentary material to make rocks; 
was altogether a littoral phenomenon, and ocean currents had 
no essential agency in its accomplishment. Continental 
masses were constantly being removed by atmospheric erosion, 
and the comminuted material carried into the adjacent ocean 
basins. This sediment was transported only so far as the 
velocity of the water could carry it, hence all coarse material 
was precipitated as soon as still water was reached, or imme- 
diately upon the shore. But a large part of the material 
brought down by our rivers was taken into solution, hence 
this material contributed little to the filling of the ocean 
basins. The deposit made at a distance of one hundred miles 
from shore, where the water is five hundred feet or more in 
depth, is almost entirely organic, derived from the decompo- 
sition of the tissues of the animals inhabiting the sea. All 
our sedimentary rocks are formed under water, and mark 
encroachments of the sea. The sea, when invading the land, 
carries forward its beach line, formed by shore waves, as an 
unbroken sheet as far as the encroachment extends. This 
gives us a sheet of sand or gravel, if the shore affords 
materials from which sand and gravel can be formed. Above 
this, we have the deposit of the more quiet water, a little off 
shore, fine sand and clay; then a mingling of organic and 
mechanical sediments ; finally, where deep water prevails, of 
pure organic materials, ze. limestones. Each inundation of 
the land has given us such a cycle of deposits, and nearly all 
of the great geological formations consist of such a series, 
coarse sandstones, and conglomerates below, then argillaceous 
rocks mixed with lime, then pure limestones. The Potsdam, 
Calciferous and Trenton, the Medina, Clinton and Niagara, 
the Oriskany, Schoharie and Corniferous;: the Portage, 
Chemung and Sub-Carboniferous limestone and other strata 
above form such cycles of this series. 
Another interesting fact brought to light by Count 
Pourtales, was the formation of compact hard limestones in 
the organic belt, as the immediate product of deposition. He 
