158 Tertiary. 



Pecten virginiaaus, Ostrea 2yercrassa, O. suhfalcata, 0. sculjjfurafa, O. 

 ilisparilis.1 Ilyoconcha incarva, Ifodiola ducateli, now Volsella diica- 

 teli, Byssoarca marylandica, and JLrca caUipleura. 



Prof. Emmous* described the Tertiarj^ of Lake Cham plain as con- 

 sisting of clays and sands, embracing, to some extent, marine shells of 

 recent age — the whole formation in Essex count_y, New York, not ex- 

 ceeding fifty feet in thickness, and averaging only from twenty to 

 twentj'-five feet. From above, downward, the strata are, first, a fine 

 white, or yellowish white, marine sand; second, a ^-eliowish clay; and 

 third, a blue clay. The yellowish clay abounds with argillo-calcarcons 

 concretions, of all shapes and forms, which appear to have been formed 

 by molecular attraction, .since the deposition of the beds. 'On the 

 New York side of the lake, it does not form a continuous deposit from 

 the head of the lake to its outlet, but interruptions occur where the 

 older strata reach the lake shore. On the Vermont side, it covers a 

 much greater extent of surface, and reaches from the lake to the base 

 of the Green Mountains, or from six to twelve miles. The height 

 above the level of the lake to which it extends, is about two hundred 

 feet. This an3ient sea occupied the Champlain basin, and the Hud- 

 son forming a continuous arm from the Gulf of St. Lawrence to the 

 mouth of the Hudson, at New York. 



In 1839, Prof. Charles T. Jacksonf mentioned a recent marine 

 Tertiary deposit, at Augusta, Maine, eighty-two feet above the level of 

 the Kennebec river, where it is said to form the substratum of a large 

 portion of the valley. 



Wm. B. and Henry D. RogersJ described the Tertiary in the 

 counties of Lancaster, Northumberland, Richmond, Westmoreland, 

 King George, and the eastern part of Stafl:brd, in Virginia; thus in- 

 cluding the peninsula between the Potomac and Rappahannock rivers. 

 This area forms the northern portion of the Tertiary of Virginia. 

 The Miocene extends from near the bay shore, westward over the 

 larger portion of the peninsula, while the Eocene occupies the remain- 

 ing area on the west. They descril)ed from the Miocene, Turritella 

 flnxionalis and Fasciolaria rhomhoidea; and from the Eocene, 

 Cytherea lenticularis, now Dosiniopsis lenticidaris, Crassatella capri- 

 cranium, Cucullaea ononcheila, now Latiarca ononcheila, C. trans- 

 versa, now L. transversa and Venericardia ascia. 



* Geo. Rep. N. Y., 1838. 



f Third Annual Rep. Geo. of Maine. 



X Trans. Am. Phil. See, vol. vi. 



