ON REMAINS OF PRIMITIVE ART IN THE BRIDGER BASIN OF 



SOUTHERN WYOMING. 



By Professor Joseph Leidy. 



Fort Bridger occupies a position iu the midst of a wide plain at the 

 base of the Uiutah Mountains, and at an elevation of upward of G,000 

 feet above the sea-level. The neighboiinf'' country, at a remote geolog- 

 ical period, appears evidently to have been occupied by an immense 

 fresh-water lake, and the ancient lake-deposits now form the basis of 

 the region. These deposits have been subjected to a vast amount of 

 erosion, resulting in the production of deep valleys and wide basins, 

 which are traversed by Green Eiver and its tributaries. From the 

 valley of Green River, the ancient lake-deposits rise in succession as a 

 series of broad table-lauds, or terraces, and narrower iiat-toj^ped hills, 

 which extend to the flanks of the surrounding mountains. 



The snows of the Uintah, Wahsatch, and other mountain-ranges are 

 a never-failiug source of supply to the principal streams; but most of 

 the lesser branches, dependent for their supply on the winter snows of 

 the lower hills and plains, completely dry up on the advance of summer. 



The country for the most part is treeless, and destitute even of large 

 shrubs, except along some of the water-courses and iu some of the 

 narrower valleys. At a greater elevation the higher foot-hills and 

 flanks of the Uintah Mountains are covered with a dense forest growth, 

 from which the rocky summits of the latter project, as bare of vegeta- 

 tion as the plains below. 



The elevation of the Bridger Basin and the very little rain-fall of the 

 region are conditions unfavorable to a luxuriant vegetation. The priu-. 

 cipal growth of the plains consists of sage-bushes, {Artemisia tridentata,) 

 intermingled, however, with many other less abundant, and, in proper 

 season, bright-flowered plants. Wide, bare, path-like intervals sepa- 

 rate the bushes, or the interspaces are occupied by scanty grasses. 



The flat-topped hills or table-lands arising from the valleys and 

 extended plains, independent of the higher mountain-ranges, form the 

 most characteristic feature of the landscapes in Southern Wyohiing. 



The flat-topped hills or terraces, worn into all sorts of shapes, some- 

 times appearing in the distance as extensive fortitications, at others as 

 great walled cities, huge castles, pyramids, mounds, &c., are familiarly 

 known under the name of buttes. This word is of French origin, and 

 signifies a bank of earth or rising ground. Similar features under simi- 

 lar conditions are frequent in many parts of the continent west of the 

 Mississippi. 



The buttes in the neighborhood of Fort Bridger are composed of 

 nearly horizontal strata of various colored indurated clays and sand- 

 stones. In most localities visited by the writer the clays predominate, 

 and are usually greenish, grayish, ash-colored, and brownish. When 

 unexposed they are compact, homogeneous, and of stony hardness. In 

 composition they vary from nearly pure clay to such as are highly 

 arenaceous, and gradate into those in which sand largely predominates. 

 Exposed to atmospheric agencies they readily disintegrate, and the 

 declivities of the buttes, generally destitute of vegetation, are usually 



