162 WALKS AND TALKS. 



2OCVIII. THE CElVtETTKRIKS OR THE 



TERTIARY FOSSILS. 



THE "Bad Lands" in the dialect of the trapper and In- 

 dian, are regions unfavorable to the pursuit of their occupa- 

 tions ; as the snow-covered slopes of the Alps are Monts mau- 

 dits (cursed mountains) in Savoy, and an unavailable ridge in 

 the Pyrenees is Monte maladetta to the Spaniard. The Bad 

 Lands of the United States are underlaid by Tertiary strata 

 which have been worn and wasted in innumerable fantastic 

 shapes, and excavated on so vast a scale as to expose to view 

 the relics of the creatures buried beneath the rubbish of hun- 

 dreds of thousands of years. In order of succession these 

 strata lie further than the Quaternary deposits from the com- 

 pleted surface. Still, there are extensive regions where noth- 

 ing more modern covers the wastes of the Bad Lands ; but 

 that is only because the work of geological building stood still 

 during an epoch. 



Inspect the rocks of some Tertiary district; we are pretty 

 sure to find them horizontal or nearly so. Along the Atlantic 

 and Gulf coasts, they slope gently toward the sea. In some 

 parts of the Pacific coast, the Tertiary strata have been tilted 

 to high angles and subjected to metamorphic action. In the 

 interior of the continent they generally lie in positions nearly 

 horizontal. Tertiary strata which slope down to the sea and 

 under it or once had such a slope are of marine origin, 

 and contain relics of marine populations. In the interior, we 

 find the fossil remains mostly those of fresh water and the 

 land. In some of the deepest Tertiary of the interior, the 

 aquatic forms are brackish-water species ; and those from the 

 lowest beds are sometimes salt water species. These facts are 

 important in setting in order the history of Tertiary times. 



Let us visit one of these desert spaces of the continent. 

 We leave the valley of the upper Missouri and travel over- 

 laud across plains parched by drouth and clothed only with 

 scattered sage brush. The buffalo is not found grazing here; 



