NATURAL SCIENCES OF PHILADELPHIA. 71 



Dana's map of the cretaceous epoch gives a general view of the United States 

 at this time, supposing what was then ocean had become land and fresh water. 



It is probable that the estuary deposits of Upper Missouri are the base of 

 the older eocene, and the fresh-water shells are the earliest tertiary types of 

 this continent. The species of Vivipara resemble the eocene forms of the 

 Paris basin. According to Meek and Hayden these beds are more than 2000 

 feet thick. 



Vanuxem was the first geologist who stated that a lignite bed is situated 

 in South Carolina between the cretaceous and eocene strata, and Tuomey has 

 since described several localities in that State and one in Clark Co., Alabama, 

 represented by No. 6 of his Bashia Creek section ; and No. 2 of the section 

 represents the Marlborough and Buhrstone group, or second stage of the 

 eocene. In general, some doubt rests upon the identity of species by Tuomey, 

 but the following list of shells contained in No. 2 is copied, with emendations, 

 from bis Report: Ostrea Carolinensis, Con., Venericardia planicosta, Proto- 

 cardia Virginiana ? Con., Volutilithes Tuomeyi, Con. This bed represents the 

 dark-colored loose sand of Piscataway, over which and next in succession 

 lies the Marlborough rock, which corresponds to the " great Carolinian bed" 

 of Ruffin, and the "calcareous strata of the Charleston basin" of Tuomey. 

 The sand bed and condition of its fossils, as well as the similarity of some of 

 its species, reminds us of the Bracklesham Bay locality in England, and the 

 superimposed rock of the Bognor beds. 



Although the Aturia ziczac is the only fossil of Oregon known to be identi- 

 cal with the New Jersey eocene, the vast distance between the localities will 

 account for the variation ; for the Continent was then as wide as from the 

 Appalachian to the Rocky mountains, and seems to have been intersected by 

 many rivers and fresh-water lakes, which have left an abundance of shells 

 and mammalian remains entombed in the strata deposited by their waters. 

 The Brandon fruits described by Hitchcock are all different from those of 

 Shark River, but the conditions under which they nourished may account for 

 this variation. They probably grew on high land, at some distance from the 

 coast, whilst the station of the others was on low land along the shore, where 

 Palms and Acacias scattered their fruit within reach of currents which swept 

 them into the sea. 



At present, the marine beds of this era are found to lie close to the Atlantic, 

 and in Oregon they skirt the shore ; but estuary deposits were observed by 

 Meek and Hayden in Upper Missouri. The Shark River marl is an indurated 

 clay, with disseminated grains of green sand, which are often smooth and 

 shining, and the shells are all in the form of casts, which are distorted mon- 

 or less. Portions of this clay are indurated, making it as difficult to break 

 as the hardest limestone. Its thickness is yet unknown. The Aturia of this 

 locality is discoid, which is the result of pressure, whilst the Oregon forms 

 are broader, and one specimen approximates the normal form of the Eu- 

 ropean shell. 



Professor Harper describes a deposit on Chiekasawhay River, Mississippi, 

 which also is of similar geological age. "The Nipadites and Cycadites mixed 

 with coniferous trees, and even oaks.'' "Stumps are seen rooted in the 

 ground, as smooth and even as if not cut with an axe, but sawed with a sharp 

 saw." " A little higher up, on the Chiekasawhay River, occurs the most 

 southern outcrop of the large eocene marl stratum. Above the marl lies a 

 stratum of hard limestone, which contains abundance of an Ostrea of large 

 size." In this description I recognize the strata on Savannah River, where 

 the lignite is overlaid by the " great Carolinian limestone" group, and suc- 

 ceeded by the Ostrea Georgiana, which is found as far west as Cape St. Luoa.-i 

 in Lower California. 



The lignite bed underlies the bluff at Vicksburg, where we find 1. lignite : 

 2. ferruginous rock, with Ostrea Georgiana, Conrad ; 3. St. Stephen's lime- 



1865.] 



