NATURAL HISTORY MISCELLANY. 179 
that of Florida, is probably entirely the product of organic life, and 
as such, probably the most considerable geographical feature on 
our earth’s surface the product of that agent alone. Cape Hat- 
teras, however, cannot be regarded as in any way the result of 
reef building animals, though it has been suggested that possibly 
the banks so like the reefs of Florida, may rest upon ancient 
coral deposits. Sections through the reefs show that they are 
built on clay bottoms. The Delaware and Chesapeake bays may 
be, in part, at least, accounted for by supposing that the vast ice 
streams which during the glacial period passed down the main 
rivers which lead into them, just as they poured down the Hudson 
and the Connecticut, had eroded the soft rocks upon which they 
descended from the harder rocks of the Appalachian Mountains 
just as the streams of the Rhone and Rhine had cut away the soft 
rocks making the lake basins of Geneva and Constance. We can- 
not, however, in this way account for the formation of Pamlico and 
‘Albemarle sounds, though the mud and sands which form the out- 
lying banks are probably derived from the excavation of the Chesa- 
peake, just as the similar deposits, which enclose the broad water of 
the peninsula of Eastern Virginia, are derived from the excava- 
tion of the Delaware Bay. 
It is likely that the promontory of Cape Hatteras is the result 
of the elevation of an outlying ridge of the Appalachians near 
Richmond, Virginia. At that point there is a ridge of syenite 
appearing from beneath the tertiary clays. This ridge clefts to 
the east; beneath the clays to the north, is similarly hidden, but, 
towards the south, extends as far as near Weldon, where it may 
give place to other similar ridges which continue the elevation to 
the southward. The height of this ridge can be ascertained by 
following it to the westward, where we find it sinking beneath the 
coal, the syenite lying more than a thousand feet deep, at a dis- 
tance of ten miles from the summit. So we see that Richmond is 
` on a mountain one thousand feet or more high, though covered by 
subsequent accumulations after having been much eroded. The 
mining sections through the beds of the Liassic coal field give us 
the best of evidence on this point. This ridge is parallel to the 
Alleghanies, and must be regarded as part of that system. We 
must modify our theory of the elevation of the Appalachian chain, 
so as to admit that, instead of having been altogether the product 
of forces acting during and just after the carboniferous time 
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