Mesozoic and Ocenozoic Geology and Palceontology. 277 



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 

 onlj^ 37 feet, and covering but a narrow surface area, crosses the State 

 of Maryland at Fort W^ashington; 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, bj' 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 fades of the shells has a s-trik- 

 ing generic resemblance to the living moUusca of the same latitude, 

 though none of the species are supposed to have survived. 



The marine Miocene,, beginning at Martha's Vineyard, though it maj^ 

 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 on 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 i-ange 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 



