274 J. C. BRANNER 



the Oxford clays of the English geologists.' Fabre found it in 

 crevices in Jurassic rocks, ^ but deposited in early Tertiary times, 

 while that referred to by Dr. Raymond in a corundum mine in 

 North Carolina is believed to be in eruptive rock, 3 the age of 

 which is not stated. The Irish bauxites are associated with 

 eruptive rocks of Tertiary Age.'* 



The Alabama bauxite deposits are said^ by McCalley to be 

 of Lower Silurian Age, but Hayes thinks^ the Alabama and 

 Georgia deposits were formed "toward the close of the Eocene." 



These cases are cited simply to show that bauxite is not con- 

 fined to rocks of any particular age, except perhaps in a given 

 region. I have seen it stated that bauxite has been found recently 

 near the Maumelle Pinnacles, about fifteen miles up the river 

 from Little Rock. This would bring the deposits into rocks of 

 Carboniferous Age This report lacks confirmation; I know 

 of neither bauxite nor syenite in that region. It is important 

 to notice, however, that if the writer's theory of the origin of 

 these deposits is correct, search for them in Arkansas should be 

 confined to the neighborhood of the eruptive syenites, ^ though 

 not all these syenites have bauxite deposits in their vicinity. 

 The eruptive rocks at Magnet Cove are mostly syenites, but no 

 considerable bauxite deposits have been found associated with 

 them. Some small fragments were found by me in the Cove 

 on the north slope of the hill just south of the Baptist church. 



Origin of the Arkansas bauxite deposits. — In searching for new 

 deposits and in determining the limits of those already known, we 

 must be guided to a certain extent by a knowledge of the method 



' Bull. Soc. Geol. de France XXV, 1867-8, 935. 



^BuU. Soc. G^ol. de France, 1869-70, XXVII, 518. 



3 Trans. Amer. Inst. Min. Eng. VII, 86. 



''Memoirs of the Geol. Survey [of Ireland] to accompany sheets 7, 8, 14, 20. By 

 R. G. Symes. 



5 Alabama bauxite. By Henry McCalley. Proc. Ala. Ind. and Sci. Soc, 

 1892, II, 21. 



® Bauxite. By Charles W. Hayes, i6th Ann. Rep. U. S. Geol. Sur., Part III, 

 592. Washington, 1896. 



^ For the distribution of eruptive rocks in Arkansas see Vol. II o f the annual 

 report of the Geological Survey of Arkansas for 1890. 



