TITLES AND ABSTRACTS OF PAPERS 87 



Silurian age. Both minerals are found in the Keokuk, in southeastern Iowa, 

 as geodes. Doubtless many are familiar with other occurrences which are not 

 known to me. The presence of zinc and lead from so many localities and 

 different geological horizons can be no accident. From all the above places 

 igneous rocks seem to be absent. It seems as if the metals must have been 

 derived from associated or previously overlying eroded limestones. In my 

 opinion, it is not necessary that the metals should have been originally pre- 

 cipitated in sulphide form, but as carbonates. The metals found commonly in 

 such ore deposits are Ca, Ng, Fe, Zn, Mn, Ba, Sr, Pb, and Cu. All but the 

 last occur in the isomorphous calcite and aragonite groups. Meigen has shown 

 that various invertebrates secrete both calcite and aragonite shells or skele- 

 tons. When the animal forms a shell of calcite it should also take up a cer- 

 tain amount of Mg, Fe, Mn, and Zn. If it secretes an aragonite shell it is 

 likewise to be expected that it will absorb some Sr, Ba, or Pb. Van Ingeu 

 and Phillips have recently shown that the bodies of gastropods, crustaceans, and 

 echinoderms also constantly contain Cn, Fe, Zn, and Mn, with Pb occasionally. 

 This is additional evidence that limestones must contain disseminated metals. 

 I have nothing to say as to how this type of ore deposits reached their present 

 position. Of course, the lateral vsecretion theory of Sandberger or precipita- 

 tion by descending waters have prevailed ; but I have no objection to Doctor 

 Tarr's theory of ascending waters, and I certainly feel that we have good 

 reasons for considering the limestones as the direct source of the metals, 

 although I also feel that the metals originally came into sea-waters by the 

 decomposition of minerals from igneous rocks. 



Mr. H. A. Wheeler : The permeability of compact limestone is well illus- 

 trated in a bed of very compact, close-grained lithographic limestone that 

 occurs in a quarry on Barton and First streets, in south Saint Louis, in the 

 upper portion of the Saint Louis limestone. Blocks of this seemingly imper- 

 vious rock that show no seams to the eye are found to contain vugs or cavities 

 one to six inches in size when broken open. These vugs are lined with curved 

 rhombic pink crystals of dolomite, through which project beautiful complex 

 crystals of prismatic calcite, and the remaining space is more or less completely 

 filled with millerite, or sulphide of nickel, in a filiform or hairlike form. 

 Occasional small crystals of gypsum, galnite, and sphalerite also incrust the 

 calcite crystals. The Emistein mine, 10 miles west of Frederickstown, Mis- 

 souri, alluded to by Professor Tarr, is the largest and strongest fissure vein 

 thus far found in the granitic area of southeast Missouri, but smaller, non- 

 profitable, quartz veins in the granite and porphyry are quite frequently found 

 that usually carry more or less argentiferous galena or copper sulphides. The 

 silver content is usrually not large, 5 to 25 ounces per ton, and the veins are 

 apt to be only a few inches in width, "with a quartz filling. 



RELATION BETWEEN OCCURRENCE AND QUALITY OF PETROLEUM AND 

 BROAD AREAS OF UPLIFT AND FOLDING 



BY EUGENE WESLEY SHAW 



(Abstract) 



In attempting to find the cause of the fact that most of the oil and gas 

 o(;curs in geosynclines, and that there seems to be some relation between the 

 VIII— BrTLL. (Jkol. Sor. Am.. Vol. 29, 1917 ' 



