THE BAUXITE DEPOSITS OF ARKANSAS 273 



2 inches iron (limonite.) 



6 inches pink and white clays. 



The pink and white clays at the bottom of this well belong 

 with the horizontally stratified Tertiary beds of the neighbor- 

 hood. There are no fossils, however, in these clays, and they 

 are considered as Tertiary solely upon lithologic and strati- 

 graphic grounds. 



At Tarplay's place in the northwest corner of section 36, i 

 north, 12 west, the bauxite has a thin bed of Tertiary or post- 

 Tertiary sandstone overlying it. At Mabelvale in i south, 13 

 west, section 10, northwest quarter, the same kind of ferruginous 

 sandstone overlies bauxite. It should be added also that the 

 bauxite at several places overlies the eruptive syenites or so- 

 called "granites," while at several others it is very probable 

 that there are syenites beneath them. These syenites are 

 apparently of late Cretaceous or post-Cretaceous Age. 



It is not to be inferred, however, that bauxite is confined to 

 Tertiary rocks, except perhaps in Arkansas. I see no reason 

 why the conditions that produce this mineral might not exist in 

 one age as well as in another, though these conditions are likely 

 to occur in one age in one place and in another age at 

 another place. 



The statement of Laur that " the phenomena which gave 

 rise to the bauxites in Europe occurred with great intensity 

 toward the end of the Cretaceous epoch, and has never been 

 repeated"' is probably unwarranted. 



In southern France bauxite is said to form the parting 

 between the Cretaceous and the Jurassic. Coquand says it is 

 in the Lychnus beds of the Upper Cretaceous.^ Collot shows 

 that it lies between the Urgonian below and the Cenomanian 

 above, that is, about the junction between Lower and Upper Cre- 

 taceous. 3 Rouville says the pisolitic iron of Herault is in the 

 "Oxfordian" or Upper Jurassic, if by " Oxfordian " he means 



■Trans. Amer. Inst. Min. Eng. 1896. 

 ^Bull. Soc. Geol. 1870-1, XXXVIII, iii. 

 3Compt. Rend. 1887, CIV, 129-130. 



