INTERPRETATION OF ENVIRONMENTAL CONDITIONS 209 



of this has been attempted by the author in PubHcation 207 of the Carnegie 

 Institution, page 62. 



It can scarcely be possible that the highlands mentioned failed to share 

 in the general elevation of the continent during Pennsylvanian and Permo- 

 Carboniferous times, and though there is no evidence that at any place they 

 reached a height or condition sufficient to produce even incipient glaciation, 

 still the rise was enough to afford an abundance of deposits under red-beds 

 conditions. Indeed, the source of supply seems inadequate to furnish the 

 amount of material that has been accumulated, and this is probably why 

 Schuchert has suggested so remote a source of supply as Columbia. 



As has been said, the red beds of the northern part of the Plains Province 

 are so largely buried that the outer borders are not exposed and it is im- 

 possible to say how far they extend from the edge of the Rocky Mountain 

 axis, but that the distance was not excessive is Indicated by the discovery in 

 Wyoming of red beds shading into dark-colored shales and limestones to 

 the north and east in Wyoming (Carnegie Inst. Wash. Pub. No. 207, p. 62). 

 What the relation to the land on the eastern side of the northern portion 

 of the Plains Province may have been we have no means of knowing. 



In the southern portion of the Plains Province It is evident from the 

 data furnished in the summary description that the red beds material came 

 largely from the south and west and that a considerable body of water lay 

 to the southeast which occasionally spread north and west over portions 

 of north-central Texas for limited periods; the marine conditions seem to 

 have lingered longest in Kansas and perhaps Nebraska. 



The origin and source of the red sediments have been the cause of con- 

 siderable discussion. Two writers in particular have drawn pictures of the 

 Texas-Oklahoma portion of the province which are worth consideration 

 at this point. Beede,^ in discussing the origin and color of the deposits 

 in Oklahoma, says: 



"In tracing the limestones and shales of the basal Permian beds of Kansas 

 southward into Oklahoma the relationship of the light-colored sediments to the 

 red sandstones, red shales, and red limestones of Oklahoma Is clearly revealed. 

 It is shown that some of the heavier ledges of limestone first become sandy 

 along their outcrops in patches a few rods across. Farther south the sandstone 

 areas increase in size until the limestone appears only in local areas In the sand- 

 stones and is finally wanting. Traced farther southward, the sandstones become 

 deep red or brown, with local areas of white. The decimation of the fauna sets 

 in as the limestones diminish and the remains of life are not found far beyond the 

 limits of the limestones. The shales become red very much farther north than 

 do the sandstones, and are frequently moie deeply colored. Some of the lower 

 limestones become red before they change into sandstones. The sandstone ledges 

 continue for some distance southward as rather even, uniform beds, but farther 

 on they are found to thicken and thin in a somewhat systematic manner. 



^ Beede, J. W., Origin of the Sediments and Coloring Matter of the Red Beds of Oklahoma, 



Science, vol. xxxv, pp. 348-350, 1912. 

 15 



