of the Lafayette Formation. 393 



even pre-Cretaceous time, while with me he still considers the 

 upper portion of the " Tuscaloosa" as being the same materials 

 re-arranged by aqueous agencies during the " Orange Sand " or 

 Lafayette epoch. This discovery changes the general aspect 

 of the latter formation in so far as I had attributed the heavy 

 gravel deposits of the Tennessee and Warrior river borders to 

 strong currents coming from the northward — as indicating the 

 course of the easternmost delta-bayou of the glacial flood ; 

 while from the point of view that these gravels are merely 

 debris torn from the ancient sub-Cretaceous beach formed almost 

 on the site of the parent rock-formation (the Subcarboniferous 

 chert), the assumption of any such large current flowing to 

 southward in that region becomes unnecessary. In fact, it 

 becomes possible that even the older border gravels of the 

 Tennessee river may have traveled in the reverse direction, 

 down the present Tennessee valley ; and we gain an insight 

 into the origin of the enormous gravel masses of that region 

 without resorting to any violent hypotheses concerning events 

 in Quaternary time. 



Another point involving a former error of interpretation on 

 my part is the recognition of the Cretaceous age of the lower 

 portion of the profile at the " Big Hill " near Pocahontas, 

 Teun., that in my report of 1860 (p. 16) is figured and de- 

 scribed as a conspicuous " Orange Sand " locality. Now that the 

 rains of thirty-five years have sculptured the smooth sides of the 

 original cut, it is easily seen that the lower portion is not of 

 the Lafayette character, and that the clay basin then supposed 

 by me to contain here, at least, vestiges of the Lafayette flora, 

 is therefore referable to a time anterior even to the Tertiary ; 

 probably the Ripley Cretaceous. 



It would seem natural and logical to seek for the record of 

 changes of level concerning the Mississippi valley — the great 

 central drainage basin of the continent — in the border lands of 

 the Gulf into which this drainage passes ; but for years I have 

 sought in vain to impress this point of view upon those in 

 whose hands lay the power for initiating such researches. It 

 thus happens that prior to the time when McG-ee's researches 

 carried him into the field where I had previously worked, the 

 discussion of the continental changes of level was carried on by 

 geologists working at the head of the great valley, largely irre- 

 spective of what is recorded near the only datum-plane to which 

 such oscillations can legitimately be referred ; since the Archaean 

 highlands of the northeast form a pivotal area from beyond 

 which no reasonable conjectures can be translated, the Missis- 

 sippi axis being known to be a line of weakness and unstable 

 equilibrium, whose movements have been largely independent 

 of those of the Atlantic coast. Witness the peculiar develop- 



