THE MAKIXG OF THE GEOLOGICAL TIME-SCALE. 2)7 



system is found along the Atlantic and Gulf borders in beds 

 of clay, sands, green sands, and chalky limestone containing 

 typical Cretaceous fossils. 



Tertiary System — The Tertiary System was first defined 

 and the name specifically applied by Cuvier and Brongniart to 

 rocks of the Paris Basin." The system so named included 

 the fossiliferous rocks lying superior to the Cretaceous system, 

 the upper member of the Secondary. As now understood, it 

 includes the three divisions, defined by their fossils, and 

 named by Lyell, Eocene, Mioceiu^ and Pliocene, typically 

 exhibited in France and England in several places. The three 

 divisions of the typical Tertiary of eastern North America are 

 the Alabama, Yorktown, and Sumpter formations. For the 

 West the series consists of Laramie, Wahsatch, Green River, 

 Bridger, Uinta, White River, and Niobrara beds, some of 

 which are fresh- water deposits. f 



Quaternary System. — Quaternary System was applied by 

 Morlot, in 1854, to the rocks or geological material lying 

 above the typical Tertiary deposits. :{: But the term " Quar- 

 ternaire " was used by Reboul as early as 1833. § The system 

 is divided into the Pleistocene and Recent, and is distinguished 

 by the presence of traces of man. In North America the 

 deposits so named are classified as Glacial, or drift, from the 

 evidence of glacial agency in their arrangement, Chaniplain, or 

 Diluvial and Alluvial, or materials distributed by waters of 

 melting glaciers and by river action, and the River To-racw or 

 Recent Period. 



Fossils the Means by which the Age of a System is Determined. 

 — These systems, although actually arbitrary groupings of the 

 stratified rocks of particular regions, have come into common 

 use as the primary divisions of the rocks whenever chrono- 

 logical sequence is considered. In describing any newly dis- 

 covered fossiliferous strata in any part of the earth, the first 

 step to be taken, in giving them a scientific definition, is to 



* " Descriptions geologiques des environs de Paris," 2d ed., 1S22, p. 9, 

 f See for details and nomenclature of the subdivisions of the systems, in 

 this and other cases, Dana's " Manual of Geology," 4ih ed., 1S95. 

 X Bull. Soc. Vaudoise de Sci. Nat., iv. p. 41. 

 § " La Geologic de la Periode Quarternaire," 1S33. 



