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Mesozoic and Cenozoic Geology and Paleontology. 135 
| Before we proceed, however, with the fresh-water or lake drift 
of the central region, it may be proper to recapitulate some of the facts, 
which we have already considered, and to call further attention to the 
total absence of evidence to support the theory of a Glacial Period. 
The marine Eocene, commencing in New Jersey, with a thickness of 
only 37 feet, and covering but a narrow surface area, crosses the State 
of Maryland at Fort Washington; Virginia, by the way of Fredericks- 
burg, Richmond and Petersburg ; North Carolina, by way of Newbern 
and Wilmington; South Carolina, by way of Charleston and Shell 
Bluff, on the Savannah river; Georgia, by way of Milledgeville; Ala- 
bama, by way of Claiborne; and Mississippi, by way of Jackson and 
Vicksburg. In South Carolina, it covers a large area, and attains a 
thickness of 1,000 or 1,100 feet. In its surface expansion, it is ex- 
posed in Florida, and reaches up into Tennessee, where it is called the 
Porter’s Creek Group and Orange Sand, and attains a thickness of be- 
tween 800 and 900 feet. In Alabama and Mississippi, it is subdivided 
into the Vicksburg Group, Red Bluff Group, Jackson Group, Claiborne 
Group, Buhrstone Group, and Flat Woods and Lagrange Lignitic 
Group, and covers a large area, and attains a thickness of 872 feet. It 
crosses Louisiana, and offers numerous exposures in Texas. It also 
appears in limited exposures in California. But nowhere is it con- 
formable with the underlying rocks. It is extremely fossiliferous in 
many of its exposures, and the general facies of the shells has a strik- 
ing generic resemblance to the living mollusca of the same latitude, 
though none of the species are supposed to have survived. 
_ The marine Miocene, beginning at Martha’s Vineyard, though it may 
exist as far north as the State of Maine, crosses New Jersey through 
Cumberland county, and forms a border upon the east and south of the 
Eocene exposures, a large part of the way to the Mississippi river, and 
west across the States of Louisiana and Texas. It is not conformable 
with the Eocene, and in some parts does not, therefore, intervene be- 
tween it and later deposits, as in South Carolina for instance its very 
existence has been doubted. But oa the western coast, and especially 
in California, it is highly developed. Between Canada de las Uvas and 
Solidad Pass the thickness is 2,500 feet, and in other places the maxi- 
mum is evidently much greater. The Coast range is composed in 
large part of strata of this age, and hence its elevation has been since 
the Miocene period. As far as we may be able to judge of the climate 
and temperature of this period, by the fossils obtained from this region, 
it was the same that it is now; and, indeed, we might go far anterior to 
