74 



SCIENCE 



[N. S. Vol. L. No. 1281 



occurs a bed several feet thick. It contains an 



abundance of the typical fossils. 



Iowa's geological centenary: Charles Keyes. 



That modern geology in America had its begin- 

 nings in Iowa appears to be not generally known. 

 Before Thomas Nuttall's famous trip down the 

 Mississippi Eiver in 1809, and his extensive appli- 

 cation of William Smith's principles of determin- 

 ing the relative age of rock terranes by means of 

 their contained fossils American geology was dis- 

 tinctly Wernerian in aspect. The eminent Ger- 

 man never had a stronger advocate than William 

 McClure, president for many years of the Amer- 

 ican Philosophical Society, of Philadelphia. It 

 was Iowa's particular mission to be the ground 

 where the fossils were collected and the materials 

 first critically compared with the organic re- 

 mains of the mountain limestones of Derbyshire, 

 England. There are a score or more important 

 episodes in the history of American geology 

 which first found light of da,y in Iowa. 

 Tertiary gravels of nortliem Utah: Chakles 

 Ketes. 



The recent tracing of the Bozeman gravels of 

 Montana over the crest of the Rockies into Bouth- 

 ern Idaho suggests their unlbroken continuity 

 farther to the south. They there seem to connect 

 with the gravel beds exposed in the Red Rock Pass 

 region and beyond in northern Utah, which have 

 long remained a puzzle to all who have worked in 

 that field. The fact that the gravels at the Pass 

 appear to have been moving southward at the 

 time of their deposition also has an important 

 bearing upon the genesis and duration of the old 

 Bonneville lake. 



Louisian vs. Mississippian as a periodic title: 

 Charles Keyes. 



If we are to retain a geographic designation for 

 the Early Carbonic rocks of America there is a 

 valid term which has by a full decade priority over 

 Mississippian. This is St. Louis, or, as we would 

 call it in these enlightened days, Louisian. It is 

 a name that was originally proposed for what was 

 supposed to be the exact section covered by the 

 Mountain Limestone as displayed in Derbyshire, 

 England. Subsequent severe restriction of the 

 name St. Louis to a single terrane and its wide use 

 in this sense do not militate in the least against 

 its first employment. A more satisfactory usage 

 of the term Mississippian is as a serial title for a 

 provincial succession, as recently proposed. 

 Possible errors in Pleistocene field-ohservations : 

 B. Shimek. 



A discussion of the value of root-tubules, cal- 

 careous content, fossils, etc., in determining the 

 age of loess deposits; also certain dangers in the 

 use of physiographic criteria in determining the 

 age of Pleistocene deposits. 

 Eelicina occulta Say: B. Shimek. 



Additional notes on the distribution of this 

 species. Both recent and fossil forms are dis- 

 cussed. 



Physics and Psychology 

 Some structural features of selenium deposited iy 



condensation from the vapor state above the 



melting point: L. E. Dodd. 

 The sublimatioii curve for selenium crystals of the 



hexagonal system: L. E. Dodd. 

 Superposed strobosoopic velocities: L. E. DODD. 

 Tlie relation between voltage atnd candle-power in 



modern incandescent lamps: Wm. Kunerth. 

 The action of conical horns: G. W. Stewart. 

 The binawral difference of pliase effect: G. W. 



Stewart. 

 Some preliminary results on the photoelectric 



longwave length limit of the metals (platinum 



and silver) : Otto Stdhlman, Jr. 

 A new non-inductive resistance: H. L. Dodge. 

 A new wall rheostat of large current capacity: H. 



L. Dodge. 

 The solar eclipse of June 8, 1918 (illustrated) : 



D. W. Morehouse. 

 The effect of temperature in resistance and specific 



resistance of tellurium crystals: Arthur E. 



FORTSCH. 



Evaluation of mental tests as used in the army: 



C. E. Seashore. 

 The distribution of musical talent in the freshman 

 class in the university: C. E. Seashore. 



James H. Lees, 

 Secretary 



SCIENCE 



A Weekly Journal devoted to the Advancement of 

 Science, publishing the official notices and pro- 

 ceedings of the American Association for 

 the Advancement of Science 



Published every Friday by 



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LANCASTER, PA. GARRISON, N. Y. 



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EDteted in the pott-«£c« at Lancaster. Pa., as saoond clasa matta 



