258 ENVIRONMENT OF VERTEBRATE LIFE, ETC. 



consists essentially of the area occupied by this sea and the terrestrial de- 

 posits formed upon the land laid bare by its contraction. 



The uplift of the continent, apparently, did not raise the Missouri land 

 sufficiently to produce any large accumulation of red sediments; if any were 

 formed they have been completely removed by erosion on the central- 

 eastern side of the province, or such small remnants as may persist are 

 hidden beneath the glacial or younger deposits of soil. On the southern and 

 western sides the uplift of Ozarkia and the Rocky Mountain barrier was suffi- 

 cient to furnish enormous quantities of material under the changed climatic 

 conditions. So great, indeed, is the amount of Permo-Carboniferous "red- 

 bed" material that the source as now revealed is entirely inadequate, and 

 some authors, notably Schuchert, are inclined to believe that a considerable 

 portion of the material in the southern part of the Plains Province must 

 have been derived from the elevated area in southern Texas and northern 

 Mexico, the old positive element, Columbia. In this southern portion of 

 the Plains Province red sediments accumulated until they spread far and 

 wide, principally to the south, west, and north of the land, and finally 

 partially buried their source. 



In a similar way the Rocky Mountain barrier between the Plains and 

 Basin Provinces furnished red sediments which were spread out on the 

 eastern face of the barrier and for an unknown distance out upon the Plains 

 Province, where they are now hidden by overlying younger deposits. In 

 the south these sediments can be traced west from the barrier until they 

 approach very closely to those derived from Ozarkia, but the actual meeting 

 of the two, if it occurs, is hidden under the southern part of the Staked 

 Plains. Farther to the north, in the latitude of Tucumcari, New Mexico, 

 the exposed red beds are Triassic in age; these may be traced to the great 

 sandstone plateau east of Las Vegas and picked up again on the edge of the 

 mountains. If any Permo-Carboniferous material occurs in this region, its 

 exposure is confined to a narrow strip on the eastern slopes of the foot-hills 

 which continues through northern New Mexico into southern Colorado. 

 What the extent of the buried Permo-Carboniferous sediments may be we 

 can not tell, for the similarity between the late Paleozoic and Triassic red 

 beds is so great that they can not be distinguished in well records. 



From Canyon City, Colorado, north to the Black Hills, the red sediments 

 continue unbroken and unchanged, indicating a similarity of conditions 

 amounting to identity in climate, height of the barrier, and all inorganic 

 factors. The total absence of any trace of land vertebrates is inexplicable; 

 by all evidence of the sediments the environmental conditions were strikingly 

 similar to those existing in Texas and Oklahoma. So many men have gone 

 over these beds in the hope of finding vertebrate fossils that some fragments 

 of bone, at least, would have turned up had the animals existed in any 

 abundance. Some, as yet not realized, factor of distribution of the sedi- 



