630 



SCIENCE 



[N. S. Vol. XXIX. No. 746 



extent and duration of the periodic submergences 

 and emergences. 



The paper was discussed by Mr. B. Willis. 



Revision of the Paleozoic Systems in North Amer- 

 ica: E. 0. Ulbich, Washington, D. C. 

 Following a brief statement of current and 

 earlier classifications of the Paleozoic rocks and 

 of the evidence, almost solely paleontologic, upon 

 which the present classification is founded, a new 

 grouping of the formations was suggested. The 

 proposed classification is based primarily on 

 crustal movements, diastrophism, the succession of 

 which is determined by the faunal evidence. The 

 occurrence of such movements is determined, aside 

 from plain physical evidence, primarily by muta- 

 tions in the faunas, especially by the introduction 

 of new faunal elements and facies, and their rela- 

 tive importance by ( 1 ) the extent and direction 

 of the submergences and emergences of land- 

 masses induced by the movements and (2) the 

 degree of the corresponding faunal mutations. 

 In determining the boimdaries of the various 

 kinds of units, formations, groups, series and 

 systems, the introduction of the new faunal ele- 

 ments is insisted on as an essential factor, second 

 in importance only to positive evidence of crustal 

 movements, in producing a scheme of classification 

 having the desirable features of (1) simplicity of 

 arrangement and expression, (2) sharp definition 

 of the major groups, (3) approximate coordina- 

 tion in time values of the various classes of units, 



(4) a high degree of accuracy in correlation of 

 geographically separated stratigraphic units and 



(5) the elimination of such hybrid terms as 

 Cambro-Ordovician and Devono-Mississippian. An 

 attempt was made to express the extent and direc- 

 tion of submergences and emergences graphically 

 by a series of curves which it is believed show an 

 appreciable rhythm in occurrence. Considering 

 that the evolution of the scheme involves the 

 determination of the essential contemporaneity of 

 many hitherto not satisfactorily related geologic 

 events, some time was devoted to the discussion 

 of such of the principles of correlation as have 

 been proved by field experience to have the great- 

 est practical value. 



Among the changes proposed, the most impor- 

 tant is a new system, the Ozarkian, comprising a 

 number of long-misunderstood formations, typic- 

 ally represented in southeastern Missouri and 

 northern Arkansas, but found also in the Appala- 

 chian Valley from New York to Alabama, in the 

 upper Mississippi Valley, in Oklahoma, central 

 Te.xas and elsewhere. Both the upper and lower 



boundaries of the Ozarkian are defined by more or 

 less marked unconformities. Often the base is in 

 contact with Acadian Cambrian, but at other 

 localities a series of beds or formations, commonly 

 referred to as " upper Cambrian," intervenes. 



The top is succeeded by one or another of a 

 great range of formations. In the most complete 

 sections the next strata are of Beekmantown age, 

 in others, however, the succeeding bed is much 

 younger. Concerning the fauna of the Ozarkian, 

 it is to be said that the trilobites and brachiopods, 

 though all new, remind one strongly of preceding 

 Cambrian types. The other classes, among them 

 a host of gastropods and cephalopods, are quite 

 different and on the whole closely allied to Ordo- 

 vician genera and species. 



Suggested changes of comparatively minor im- 

 port were (1) the correlation of the Richmond 

 with the Medina and, hence, the removal of that 

 group to the Silurian; (2) the restriction of the 

 Devonian to the lower and middle Devonian of 

 current classifications and the transfer of the 

 upper Devonian to the next younger system; 

 finally (3) it was argued that the Meramec and 

 Chester groups of the present Mississippian con- 

 stitute another system coordinate in value to the 

 Silurian and Devonian. 



Mr. Ulrich's paper was interrupted by adjourn- 

 ment at 5:45 P.M. and the reading was finished 

 on Thursday. It was discussed by Professor A. 

 W. Grabau. 



At 7 o'clock Wednesday evening the fellows and 

 their friends, to the number of 133, gathered at 

 the Hotel Eennert and sat down together at the 

 annual dinner of the society. President Calvin 

 presided, and, after dinner, remarks were made 

 by him and Messrs. Gilbert, Penck, W. B. Clark, 

 G. 0. Smith, Brock, Chamberlin, Hovey, Gulliver, 

 Van Hise, Emerson and Stevenson. 



The society convened again at 9:45 o'clock 

 Thursday morning, President Calvin being chair- 

 man, and after hearing sundry announcements by 

 tlie secretary listened to the reading by the secre- 

 tary of the following report from Professor T. A. 

 Jaggar, Jr., chairman of the committee on earth- 

 quake and volcano observations: 



" Acknowledgments have been received from the 

 governors of the Leeward Islands, of Hawaii, of 

 Jamaica and of St. Thomas, from the chairman 

 of the Isthmian Canal Commission and from the 

 secretaries of the Smithsonian Institution and of 

 the committee on seismology of the American 

 Association for the Advancement of Science. 



" Hon. W. F. Frear, governor of the Hawaiian 

 Islands, writes: 



