282 



SCIENCE 



[N. S. Vol. XXXVIII. No. 973 



M. Foote on 

 Meteorites. ' ' 



Factors in the Exchange Value of 



The section was called to order at the usual 

 meeting-place in the American Museum of Natural 

 History by the chairman, Professor J. Edmund 

 Woodman, at 8:25 p.m., May 5, 1913. Thirty-five 

 persons were present. 



Following the acceptance of the resignation of 

 Charles T. Kirk, secretary of the section. Dr. A. B. 

 Picini was recommended to the council of the 

 academy for election to that office. 



The following papers were read by title: 



"A Contribution to the Geology of the Wasatch 

 Mountains, Utah," by Mr. Ferdinand F. Hintze, 

 Jr. 



"Physiographic Studies in the Allegheny Pla- 

 teau, Particularly along its Western Margin in 

 Ohio and Kentucky," by Dr. Jesse E. Hyde. 



' ' A Limestone Dike in Southern Ohio, ' ' by Dr. 

 Jesse E. Hyde. 



Then was continued the discussion of Mr. R. B, 

 Earle 's paper on ' ' The Genesis of Certain Pale- 

 ozoic Interbedded Iron Ores, ' ' presented at the 

 April meeting. 



Professor Kemp was invited to open the discus- 

 sion, and inquired: (1) If there are not other 

 oolites than the Clinton horizon which have been 

 replaced by iron? (2) Would there not be stag- 

 nation of the water below the vadose region? 



Mr. Earle referred number (1) to his colleagues, 

 and replied to number (2) by saying that the 

 ' ' impervious ' ' beds are not wholly so, but only 

 more so than their contained loosely aggregated 

 beds — the iron formations. He believes, more- 

 over, that there have been fluctuations of the 

 ground water level. He observed also, in reply to 

 Professor Stevenson's inquiry at the last meeting, 

 that the fragments in the superjacent beds are not 

 directly in contact with the iron formation, and 

 eited replacement of pebbles and not of their 

 matrix, a feature also described in U. S. Geol. 

 Surve;^ Bull. 430. 



Professor Woodman, in comparing with the iron 

 ores of Nova Scotia, showed that various materials 

 are replaced, and that there are isolated granules 

 of iron ore contained in a matrix of mud, an 

 observation similar to those of Mr. Earle. Pro- 

 fessor Woodman maintains that the cavernous con- 

 solidations are unexplained by any syngenetic 

 theory; also that there is either partial replace- 

 ment or partial leaching in various regions. He 

 finds, incidentally, that the materials typically re- 

 placed are siliceous rather than calcareous. 



Professor Grabau discussed the iron ore deposits 

 of Tennessee, stating that they are replaced fossUs 

 which have not been rolled. He observed that the 

 deposits in Wisconsin have pebbles with surfaces 

 resembling desert varnish, and that the pebbles lie 

 at all attitudes. There are no fossils ; the beds are 

 lens-shaped — apparently cross-bedd«d by wind ac- 

 tion. There is little cementing silica. He believes 

 that the original sediments in these instances have 

 been replaced by iron. 



Dr. A. B. Picini followed with observations on 

 the chemistry of iron ore deposition, showing that 

 there is yet too little known of such processes in 

 nature to prophesy certainly as to oxidizing or 

 deoxidizing conditions underground. He referred 

 to Van Bemmelen's results, which show that the 

 yellow oxides of iron deposited chemically are non- 

 colloidal, while the red are colloidal. 



Mr. A. P. Picini gave account of experiments 

 still under way in which he has already secured 

 some replacement in a few hours by passing iron 

 in carbon dioxide solution through porous calcite 

 and silica at about 10 atmospheres. 



Professor A. W. Grabau 's paper on ' ' Irrational 

 Stratigraphy: The Right and Wrong Way of Re- 

 constructing Ancient Continents and Seas ' ' was 

 of the nature of a critique. It was illustrated 

 with paleographic maps by Schuchert, Ulrich, 

 Willis, and Chamberlin and Salisbury. The thesis 

 indicated that these maps are too often based on 

 paleontology alone to the neglect of the sediments 

 themselves — especially their origin. There are 

 sometimes arms of the sea across areas where the 

 origin of a bed of conglomerate woiild be ex- 

 pected. Erosion was here left out of the question, 

 and a ' ' stratigraphio hash ' ' was the result. Fur- 

 ther, basins where crinoids, corals, brachiopods, 

 etc., are found are mapped too small. 



Questions followed by Professor Woodman on 

 the probable width of Appalachia, by Dr. C. A. 

 Reeds on the connection between the Atlantic and 

 Pacific in Silurian time, on the origin of the 

 Silurian salts, and on the position of the present 

 Atlantic deep where once Appalachia, a consider- 

 able continent, is supposed to have lain. 



Professor Grabau thinks Appalachia may partly 

 have lain where the Atlantic coastal plain now is, 

 and did not extend over to the present Atlantic 

 deep; that is, was perhaps less than 500 miles 

 wide. The Silurian salts he thinks have originated 

 while the Taconic land mass lay to the eastward 

 in such a position as to cut off moisture-bearing 

 winds. Chaeles T. Kirk, 



Secretary of Section 



