July-August 1923 Vol. XXXI, No/s] 



The Journal of Geology 



Edited By 

 thomas c. chamberlin £ 



With the Active Collaboration of :''■ 



ROLLIN T. CHAMBERLIN. Managing Editor 

 Dynamic Geology 

 STUART WELLER ALBERT JOHANNSEN 



Invertebrate Paleontology Petrology 



EDSON S. BASTIN j. HARLEN BRETZ 



Economic Geology Stratigraphic Geology 



The Journal of Geology is published by the University of Chicago at the University of Chicago Press, 

 S7SO Ellis Avenue, Chicago, Illinois, semi-quarterly, on or about the following dates: February i, March 15,' 

 May I, June 15, August i, September 15, November i, December 15. ^The subscription price is $4.00 

 per year; the price of single copies is 65 cents. Orders for service of less than a half-year will be charged 

 at the single-copy rate. ^ Postage is prepaid by the publishers on all orders from the United States, 

 Mexico, Cuba, Porto Rico, Panama Canal Zone, Republic of Panama, Dominican Republic, El Salvador! 

 Argentina, Bolivia, Brazil, Colombia, Costa Rica, Ecuador, Guatemala, Honduras, Nicaragua, Peru,' 

 Uruguay, Hawaiian Islands, Philippine Islands, Guam, Samoan Islands, and Spain. If Postage is charged 

 extra as follows: for Canada, 25 cents on annual subscriptions (total $4.25); on single copies 3 cents (total 

 68 cents); for all other countries in the Postal Union 50 cents on annual subscriptions (total $4.50), on 

 single copies 6 cents (total 71 cents). ^ Patrons are requested to make all remittances payable to The 

 University of Chicago Press in postal or express money orders or bank drafts. 



The following are authorized to quote the prices indicated: 



For the British Empire: The Cambridge University Press, Fetter Lane, London, E.G. 4. Yearly 



subscriptions, including postage, £1 2s. 6d. each; single copies, including postage, 35. 6d. each. 



For Japan and Korea: The Maruzen-Kabushiki-Kaisha, 11 to 16 Nihonbashi Tori Sanchome, 



Tokyo, Japan. Yearly subscriptions, including postage, Yen 9.45 each; single copies, including 



postage. Yen 1.50 each. 



^ For China: The Mission Book Company, 13 North Szechuen Road, Shanghai. Yearly sub- 

 scriptions, including postage, $4.50; single copies, including postage, 71 cents, or their equivalents in 



Chinese money. « 



Claims for missing numbers should be made within the month following the regular month of publi- 

 cation. The publishers expect to supply missing numbers free only when losses have been sustained in 

 transit, and when the reserve stock wUl permit. 



Business correspondence should be addressed to The University of Chicago Press, Chicago, III. 



Communications for the editors and manuscripts should be addressed to the Editors of The Journal 

 OF Geology, the University of Chicago, Chicago, 111. 



Contributors are requested to write scientific and proper names with particular care and in citations 

 to follow the form shown in the pages of the Journal. 



Because of the high cost of printing, this Journal has foimd it necessary to adopt the following rules: 

 If I. If articles exceeding 25 pages in length are accepted for publication in the Journal, the cost of com- 

 position beyoiid 25 pages shall be paid by the author or by the institution which he represents, at the current 

 rates of the University Press. If 2. The cost of illustrative material, in excess of $1.00 per page for the 

 article, beyond the cost of tj^e which would have occupied the same space, shall be borne by the author. 

 If 3. The cost of corrections in proof in excess of 10 per cent of the cost of first composition, will be charged 

 to the author. If 4. While the cost of printing remains as now, the Journal cannot supply reprints with- 

 out charge, but reprints will be furnished authors at cost^ if ordered in advance of publication. 



Entered as second-class matter, March 20, 1893, at the Post-office at Chicago, 111., under the Act of March 3, 1870. 

 Acceptance for mailmg at special rate of postage provided for in Section 1103, Act of October 3, 1017, authorized Oa 

 July iSi 1918. o, y I, 



STED IN THE U.S.A. 



