July 3, 1003.] 



SCIENCE. 



21 



the Tallahatta Bulirstone, or lower Claiborne. 



While, therefore, we appear to be iu sub- 

 stantial agreement as to the characters of the 

 formation which we call Grand Gulf, we dif- 

 fer radically from Professor Dall as to the 

 place which it occupies in the stratigraphic 

 column. 



We fully concur in his statement that, " It 

 caii not be too often emphasized that no de- 

 termination of the age of its (southern coastal 

 plain) beds not based on their fauna, or the 

 fauna of beds both above and below those in 

 question, can be regarded as more than tenta- 

 tive; and such determinations in the past 

 have almost invariably proved erroneous." 



The sole purpose of our first note was to 

 prove, by the application of these very prin- 

 ciples, that the stratigraphic position of the 

 Grand Gulf beds was between the Pascagoula 

 Tertiary and the Lafayette; but since doubt 

 still remains, we wish to offer a few additional 

 considerations. 



So far as we have been able to ascertain, 

 the Grand Gulf beds themselves do not any- 

 where contain the fossils which afford incon- 

 testable evidence of their age. Dr. Hilgard 

 writes :* " Apart from this [the finding of a 

 few fragments of a turtle shell], my most 

 patient search, in hundreds of localities, has 

 failed to produce any fossil form; even the 

 leaves associated with the lignite seams being 

 so ill-preserved as to be unrecognizable." 



And though casts of fresh-water shells have 

 since been found in the formation, no de- 

 termination of its age from these has been 

 possible, f and we are thus compelled to rely 



* Loe. cit., p. 59. 



t Kennedy find.s V. plaiiicosia in Fayette sand- 

 stones, hut in basal layers which Veatch con.'riders 

 Jackson; Veatch also, in Frio clays near Bink- 

 ville. La., finds a fossiliferous (casts) layer in a 

 ferruginous rock; Harris finds I'nio and Attodotita 

 casts at Chalk Hills, La., along with leaves of 

 birch, willow and other dicotyledonous trees; 

 Meyer has mentioned casts of fresh-water sliells 

 occurring also at Grand Gulf. 



It may easily be imagined that the waters which 

 were active in transporting and depositing the 

 materials of the Grand Gulf miglit on occasion 

 carry into it fossils of an older formation over 



wholly upon the other test, viz., the fauna of 

 the beds below and above the ones in question. 



If we consider first the formations which 

 are known to overlie the Grand Gulf, there 

 is not very much to be said, but it is con- 

 clusive. 



The case in Texas is thus given by Pro- 

 fessor Hill, in a recent letter : ' The so-called 

 Grand Gulf beds of the Texas region are not 

 overlaid hy the Tertiary.' 



In Mississippi we have Hilgard's testimony, 

 as follows : " The latter (stratified drift or 

 Lafayette) is found directly capping almost 

 everywhere, the claystones and sandstones that 

 characterize the highest part of the Grand 

 Gulf group." 



In Alabama also the Lafayette is nearly 

 everywhere seen capping the Grand Gulf, and 

 we have no record of anything older than 

 Lafayette in this relation to it. The same 

 thing is certainly true with regard to western 

 Florida, and, we have no doubt, to the rest 

 of Florida and Georgia as well. 



In Bulletin 84 of the U. S. Geological Sur- 

 vey, Professor Dall says : " There is no doubt 

 that directl.y in contact with the Grand Gulf 

 beds in the Gulf states, lies the formation 

 variously recognized under the names of La- 

 fayette or Orange Sand of Hilgard. Lagrange 

 of Rafford. or Appomattox of McGee." 



So while there are localities by the tens of 

 thousands, in the Gulf states, where the Grand 

 Gulf is directly overlaid by the Lafayette, we 

 have no recorded instance of its being over- 

 laid by an.v formation older than the La- 

 fayette. 



This circumstance alone affords at least 

 presumptive evidence that the true place of the 

 Grand Gulf is high up in the geological scale, 

 and close under the Lafayette. 



Secondly, as to the underh/inf} formations. 

 In Mississippi Dr. Hilgard found no contact 

 of the Grand Gulf with any underlying for- 

 mation other than the Vicksburg limestone. 

 In connection with his description of these 



which they swept. The finding of a few Eocene 

 Miocene fossils in the Grand Gulf beds should not 

 cause any more surprise than the finding of .Sub- 

 Carboniferous fossils, for instance, in the La- 

 favette, as has often been done. 



