July 23, 1909] 



SCIENCE 



125 



unconformably upon the Cape Fear formation and 

 are overlain conformably by strata of the next 

 younger Cretaceous division and by non-conform- 

 able post-Cretaceous deposits. Fossil plants occur 

 from tlie base to the top of the division, and 

 towards the top invertebrates occur in marine 

 lenses interbedded with tlie plant-bearing beds. 

 Both the pliysical and paleontologic characters 

 point to the approximate equivalency of the for- 

 mation with the JIagothy-Matawan series of New 

 Jersey and with the combined plant-bearing Tus- 

 caloosa beds, the Eutaw formation and the lower 

 portion of the Kipley formation of Alabama. As 

 regards more distant correlations the plants seem 

 to indicate equivalency with the Woodbine divi- 

 sion of Texas, the Dakota formation of the western 

 interior, and the upper Cenomanian or Turonian 

 of Europe, while the invertebrates, which show a 

 close faunal relationship with the overlying 

 younger division in North Carolina, point perhaps 

 even more strongly to equivalency with the Tay- 

 lor-Navarro series of Texas and the Montana 

 series in the western interior, both of which 

 occupy positions not only above the Woodbine 

 and Dakota formations, respectively, but also 

 above the still higher Colorado group representa- 

 tives. There exists, therefore, a difference of 

 opinion which with the present array of facts is 

 irreconcilable; and the question of the correlation 

 of the division with deposits outside of the At- 

 lantic coast and eastern gulf regions must remain 

 an open one until additional data are procured. 

 In the paper previously mentioned the writer 

 proposed the name Bladen formation to designate 

 these beds. 



The third and youngest division, also of upper 

 Cretaceous age, consists of 700 to 900 feet of dark 

 gray, more or less argillaceous and calcareous, 

 marine sands and clays, conformably overlying the 

 Bladen formation, and unconformably overlain by 

 Tertiary and later deposits. The beds carry ma- 

 rine invertebrates indicating approximate equiva- 

 lency with the Monmouth formation of New 

 Jersey and with the upper Ripley beds of Ala- 

 bama. Employing the same criteria, the division 

 is correlated with the Navarro formation of Texas, 

 the Montana series in the western interior, and 

 the Senonian of Europe. The name Ripley forma- 

 tion was applied to this division by the writer in 

 1907, but owing to uncertainty which has arisen 

 regarding the exact meaning of this term as em- 

 ployed in the gulf region it will probably liave to 

 l)e dropped, in which case the name Burches Ferry 

 formation applied by Sloan to the southward con- 



tinuation of tlie terrane can appropriately be em- 

 ployed in North Carolina. 



In both South Carolina and Georgia equivalents 

 of all three of the divisions occurring in North 

 Carolina have been recognized, and their approxi- 

 mate areal distribution determined. 

 The Santa Maria Graphite Mines, Sonora, Mex- 

 ico: Fbank L. Hess. 



The Santa Maria graphite mines which are 

 owned by the United States Graphite Company, 

 of Saginaw, Mich., are situated about twenty 

 miles south and a little east of La Colorado, in 

 central Sonora. The country rock is a meta- 

 morphosed sandstone, ranging in fineness from 

 shaley material to conglomerates containing peb- 

 bles one and one half inch in diameter. Consider- 

 able andalusite in small crystals is developed in 

 the sandstones. The rocks are probably of upper 

 Triassic (Richmond) age. They are intruded by 

 graphite which has been the metamorphosing 

 agent. Intercalated with the sandstones are at 

 least seven beds of graphite ranging in thickness 

 up to 24 feet and standing at high angles. The 

 rocks are considerably folded and the graphite 

 beds show the effect of movement more than the 

 enclosing sandstones, so that they are in places 

 almost cut off through squeezing, while in other 

 places they show thickening. The graphite beds 

 are also intruded by granite dikes and in places 

 granite forms the walls. The graphite is un- 

 doubtedly formed through the metamorphism of 

 coal beds, which in other parts of the state are 

 to be found in the form of coke, anthracite and 

 bituminous coal. The graphite of the Santa 

 Maria deposits is entirely amorphous and from 

 the main vein averages 85 to 86 per cent, gra- 

 phitic carbon. Specimens may be picked which 

 carry 95 per cent, graphitic carbon. 



The material is shipped to Saginaw, Michigan, 

 for refining. A large part of the best pencils are 

 made from this graphite. It is also used for a 

 lubricant, foundry facings, etc. 



At the 221st meeting of the society, held at 

 the Cosmos Club on Wednesday evening. May 26, 

 Mr. S. F. Emmons spoke informally on the Cobalt 

 mining region. 



Regular Program 

 Diopside and its Related Minerals: Abthub L. 



Day. 



The formation of pure wollastonite from its 

 component oxides, lime and silica, and its com- 

 bination with magnesium metasilicate to form 

 diopside, together with a record of the character 



