TERTIARY AGE. 495 



Atlantic Tertiary Border, occurring at Gay Head, on Martha's Vineyard; in New Jer- 

 sey, in Cumberland County and elsewhere; and fossils maybe collected in the Marl 

 pits of Shiloh, Jericho, etc.; in Maryland, at St. Mary's, Easton, etc.; occurring on 

 both sides of the Chesapeake for a great distance; in Virginia, at Yorktown, Suffolk, 

 Smithfield, and through the larger part of the Tertiary region. 



The strata at Yorktown, beginning below, are (1) Clay filled with Turritella alticos- 

 tata Con., Callista (Cytherea) Sayana Con., etc.; (2) Sand, with few shells, chiefly 

 Yoldia {Nucula) Umatida; (3) a sandy bed, made up mostly of Crepidula costata, 

 Mort. ; (4) coarse ferruginous sand. Two miles off, the layer of Turritella} has changed 

 to a layer of Crepidulce ; and the continuation of the Crepidula layer is filled with Pec- 

 tens. Venus difformis, Ostrea, etc. 



At a locality on James River, Va., there are (1) a layer of shells of Pecten and 

 Ostrea, 5 feet; (2) bed of Chamce, 3 feet; (3) bed of Pectens, with Ostrece, 1 foot; (4) 

 second bed of Chamce, with Striarca centenaria Con., Panopcea rejlexa Say, 6 feet; (5) 

 bed of large Pectens, 2 feet; (G) closely compacted bed of Chamce and Venus difformis, 

 3 feet; (7) sand and clay, separated from the preceding by a thin layer of pebbles. 

 But in other localities of the same region, the beds are different. The first layer over 

 the Eocene often consists of pebbles or coarse sand. 



One of the most remarkable deposits in the Virginia Tertiary is a bed of Infusorial 

 remains, occurring near Richmond. It is in some places thirty feet thick, and extends 

 from Herring Bay on the Chesapeake, Md., to Petersburg, Va., or beyond, and is an 

 accumulation of the siliceous remains of microscopic organisms, mostly Diatoms. Some 

 of the beautiful forms are represented, much magnified, in Fig. 882, on the next pr.ge. 

 These beds have been referred both to the Miocene and to the Eocene; they are called 

 Eocene by Professor Rogers, after an examination of the region. 



A still thicker bed — exceeding fifty feet — exists on the Pacific, at Monterey; the 

 bed is white and porous, like chalk, and abounds in siliceous organisms. (Blake.) 



The fresh- water beds of the older Miocene, in the Upper Missouri region, along the 

 White River (a region called the " Mauvaises Terres," or Bad Lands), constitute the 

 White River group of Ilayden, and have a thickness of 1,000 feet or more. The lower 

 beds contain the Brontotherium , the higher are the Oreodont beds. Still higher fresh- 

 water Miocene occurs in Oregon, which have afforded Miohippus and other species. 



There are also, in the Wind River valley, and on the west side of the Wind River 

 mountains, other fresh-water deposits, 1,500 to 2,000 feet thick, called the Wind River 

 group, which may be of the same age as the White River group. (Meek and Hayden.) 



In California and Oregon, marine beds referred to the Miocene consist of sandstone 

 and shale, and are in some places 4,000 to 5,000 feet thick. They occur near Astoria, 

 on the Columbia River and the Willamette ; in the Coast ranges of California, north 

 and south of San Franciso, and also in the Contra Costa hills, just east; in the Santa 

 Inez mountains, some points in which are 4,000 feet in height; along the flanks of the 

 Peninsula range, in the latitude of San Diego, etc. Both north and south of San Fran- 

 cisco, on the coast, there are metamorphic slates, part of which are referred by Whit- 

 ney to the Tertiary. 



Sumter Period, or Pliocene. — The beds referred to the Pliocene occur in North 

 and South Carolina, extending south as far as the Edisto River. They contain forty 

 to sixty per cent, of living species of shells. (Tuomey & Holmes.) The beds are soft, 

 either loam, clay, or sand, and lie in depressions of the older Tertiary and Cretaceous 

 formations. The equivalents of these beds in Virginia and New Jersey are not clearly 

 made out; neither are they known from the Gulf States. 



In the Upper Missouri region, the White River group is overlaid by other fresh-water 

 Tertiary beds, 300 to 400 feet thick, called by Meek & Hayden the Loup River group, 

 and byMarsh the Niobrara. They contain in their upper part the remains of numerous 

 extinct Mammals, including Camels, Rhinoceroses, Elephants, Horses, etc., besides land 

 and fresh-water shells which are probably of recent species. These beds occur on the 

 Loup Fork of the Platte, north to the Niobrara, and south nearly to the Gulf. 



Phosphatic Deposits on the South Carolina Eocene beds. — The Eocene of South Caro- 

 lina, about Charleston, and in other portions of the coast region, is thickly covered with 



