VOLUME. XX” | 7 NUMBER 6 
‘THE 
A SEMI-QUARTERLY 
EDITED BY 
THOMAS C. CHAMBERLIN AND ROLLIN D. SALISBURY 
With the Active Collaboration of 
_ SAMUEL W. WILLISTON ALBERT JOHANNSEN WILLIAM H. EMMONS 
Vertebrate Paleontology Petrology Economic Geology 
STUART WELLER WALLACE W. ATWOOD ROLLIN T. CHAMBERLIN 
Invertebrate Paleontology Physiography Dynamic Geology 
ASSOCIATE EDITORS 
SIR ARCHIBALD GEIKIE, Great Britain GROVE K. GILBERT, Washington, D.C. 
SEPTEMBER-OCTOBER, 1912 
SON TEN Ts 
MICROSCOPICAL PETROGRAPHY FROM THE QUANTITATIVE VIEWPOINT 
FRED. EUGENE WRIGHT 
GLACIATION IN THE TELLURIDE QUADRANGLE, COLORADO ALLEN DAvip HOLE 
ON THE STRATIGRAPHIC POSITION AND AGE OF THE JUDITH RIVER FORMA- 
“TRTICOUIS & ss Goat acetate oS aCe at en Se epee ea Naas seen uteareaty shu Ord 20 0)-8 8 
MODIFICATIONS OF THE QUANTITATIVE SYSTEM OF CLASSIFICATION OF 
IGNEOUS ROCKS WuitMAN Cross, J. P. Ipprncs, L. V. Prrsson, H. S. WASHINGTON 
ISOSTASY, A REJOINDER TO THE ARTICLE BY HARMON LEWIS 
JoHn F. Hayrorp 
SUBMIS US 08 Ol ee eee ee ee ee 
Che Anibersity of Chicago press 
CHICAGO, ILLINOIS 
“AGENTS: 
THE CAMBRIDGE UNIVERSITY PRESS, Lonpon anp EDINBURGH 
WILLIAM WESLEY & SON, Lonpon 
TH. STAUFFER, Le1rzic 
THE - MARUZEN-KABUSHIKI-KAISHA, Toxyo, Osaka, Kyoro 
JOURNAL or GEOLOGY 
HEINRICH ROSENBUSCH, Germany CHARLES D. WALCOTT, Smithsonian Institution 
THEODOR N, TSCHERNYSCHEW, Russia HENRY S. WILLIAMS, Cornell University  - 
“CHARLES BARROIS, France- JOSEPH P.IDDINGS, Washington, D.C, 
ALBRECHT PENCK, Germany JOHN C. BRANNER, Leland Stanford Junior University 
HANS REUSCH, Norway ' RICHARD A. F. PENROSE, Jr., Philadelphia, Pa. 
GERARD DEGEER, Sweden WILLIAM B. CLARK, Johns Hopkins University 
ORVILLE A. DERBY, Brazil : WILLIAM H. HOBBS, University of Michigan 
T. W. EDGEWORTH DAVID, Australia FRANK D. ADAMS, McGill University 
* BAILEY WILLIS, Argentine Republic CHARLES K, LEITH, University of Wisconsin 
481 
502 
539 
550 
562 
570 — 
