42 THE PERMO-CARBONIFEROUS RED BEDS OF 



CLIMATIC VARIATIONS RECORDED IN THE PERMO-CARBONIFEROUS BEDS OF TEXAS. 



It is apparent from the foregoing that the Red Beds of Texas terminated 

 on the east in a Hmestone-forming sea. There was over north-central Texas 

 and central Oklahoma a great, flat area bordering the eastern sea. This 

 area received abundant terrestrial deposits from higher lands to the north 

 and west, but was of such slight elevation that it was subject to local inunda- 

 tions, both by marine waters, due to sHght oscillations of level, and by 

 fluviatile waters during humid phases of the climatic oscillations. Within 

 the limits of the eastern sea there are limestones with frequent intercalations 

 of sandstone and sandy shales, and with occasional beds of clay, such as 

 would occur in the deposits of a low and partially or recurrently flooded 

 region. That the whole area was not subject to large movements due to 

 periodic changes of level of considerable magnitude is shown by the badly 

 mixed and discontinuous character of the beds. No prevailing continuity 

 of the beds can be traced, but a study of sections i, 2, 8, and others (pp. 

 34-41) shows a considerable thickness of red clay and sandstone as the first 

 dominant series of deposits in the lower Wichita. One thing is apparent in 

 both Texas and Oklahoma: the limit of red color transcends the beds far 

 east of where the clastic material gives place to organic deposits and is 

 noticeable for a considerable distance in the limestones. 



The most generally accepted hypothesis for the explanation of the pres- 

 ence of a red color in various deposits regards it as due to the mature weather- 

 ing of iron-bearing rocks in a fairly humid region, with alternations of relative 

 drought and humidity. There is nothing in the Red Beds of Texas to oppose 

 this hypothesis or to support the alternative hypotheses that the color is 

 due either to the oxidation of the iron subsequent to its deposition or to 

 the dehydration of a limonite by the pressure of superincumbent layers, at 

 least so far as the author has been able to determine. It is here accepted 

 as the working principle in the study of the climate of the region and period. 



EVIDENCE OF CLIMATIC CONDITIONS IN WICHITA TIME. 



Few plant remains have been recovered from the eastern (lower) expo- 

 sures of the Wichita, and while this is not positive evidence of the absence 

 of vegetation during the first part of the period, the rarity of the remains 

 lends weight to the suggestion given by the prevailing red color, of a lack 

 of carbonaceous debris in the deposits. 



While conglomerates are not lacking in the lower Wichita, they are not 

 of the same character as those appearing farther to the west and higher in 

 the series. The first conglomerate above the lowest series of Red Beds is 

 described by Cummins as a "pecuHar conglomerate," consisting of fragments 

 of clay and iron ore, cemented by iron. This conglomerate is constantly 

 referred to in my notes as the "pea conglomerate."- Gordon interprets it 

 as formed of fragments which have been broken up by wave action and re- 



