TLbc S^ournal of (5eolog^ 



Vol. XXII CONTENTS FOR SEPTEMBER-OCTOBER J9I4 No. 6 



THE STRENGTH OF THE EARTH'S CRUST. V. THE DEPTH OF MASSES PRODUCING GRAVITY 



ANOMALIES AND DEFLECTION RESIDUALS {Continued) - Joseph Barrell 537 



NOTES ON THE GEOLOGY OF THE SUN RIVER DISTRICT, MONTANA 



Sidney Powers and Hervey W. Shimer 556 



CORRELATION AND STRUCTURE OF THE PRE-CAMBRIAN FORMATIONS OF THE GWINN IRON- 

 BEARING DISTRICT OF MICHIGAN ------------ R. C. Allen 560 



EVIDENCE OF THE MIDDLE-UPPER HURONIAN UNCONFORMITY IN THE QUARTZITE HILLS AT 



LITTLE LAKE, MICHIGAN - - - - - - - - - - R. C. Allen and L. P. Barrett 574 



PFVSIOGRAPHIC RELATIONS OF SERPENTINE, WITH SPECIAL REFERENCE TO THE SERPENTINE 



STOCK OF STATEN ISLAND, N.Y. ------------- W. O. Crosby 582 



THE MODE OF FORMATION OF CERTAIN GNEISSES IN THE HIGHLANDS OF NEW JERSEY. I 



' Clarence N. Fenner 594 



THE MISSISSIPPIAN ROCKS OF NORTHEASTERN OKLAHOMA L. C. Snider 613 



PETROLOGICAL ABSTRACTS AND REVIEWS 625 



REVIEWS - - ..,.-,. 630 



The Journal of Geology is published semi-quarterly, on or about the following dates: February i, 

 March 15, May i, June 15, August i, September 15, November i, December 15. Tf The subscription price 

 is I4.00 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, ^f Postage is prepaid by the publishers on all orders from the United 

 States, Mexico, Cuba, Porto Rico, Panama Canal Zone, Republic of Panama, Hawaiian Islands, Philippine 

 Islands, Guam, Samoan Islands, Shanghai. ^ Postage is charged extra as follows : For Canada, 30 cents 

 on annual subscriptions (total ^4.30), on single copies, 4 cents (total 69 cents); for all other countries in 

 the Postal Union, 53 cents on annual subscriptions (total $4.53), on single copies, 11 cents (total 76 cents). 

 T[ Remittances should be made payable to The University of Chicago Press and should be in Chicago or 

 New York exchange, postal or express money order. If local check is used, 10 cents should be added 

 for collection. 



The following agents have been appointed and are authorized to quote the prices indicated: 



For the British Empire: The Cambridge University Press, Fetter Lane, London, E.C., and 



^illiam Wesley & Son, 28 Essex Street, Strand, London. Yearly subscriptions, including postage, 



i8j. 2)d. each; single copies, including postage, y. 2d. each. 



For the continent of Europe: Karl W. Hiersemann, Konigstrasse 29, Leipzig, Germany. Yearly 



subscriptions, including postage, M. 19 each; single copies, including postage, M. 3.20 each. 



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



Tokyo, Japan, Yearly subscriptions, including postage. Yen 9.00 each; single copies, including 



postage, Yen 1.50 each. 



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

 publication. The publishers expect to supply missing numbers free only when they have been lost in 

 transit. 



Business correspondence should be addressed to The University of Chicago Press, Chicago, 111. 



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. 



Separates, if desired, must be ordered in advance of publication. Separates of leading articles will be 

 printed as ordered, of which 50 (without covers) will be furnished gratis, the actual cost of the remainder 

 (and covers, if desired) to be paid for by the author. The actual cost may vary, and will depend upon 

 the amount of work in re-making the pages into forms, presswork, paper, binding, etc. Separates 

 containing half-tones may be expected to cost somewhat more, the increase depending upon the number 

 of cuts and the amount of work required upon them. 



Entered March 20, 1893, at the Post-office at Chicago, 111., as second-class matter, under Act of Congress, March 3, 1879. 



