vi CONTENTS OF VOLUME XXVII 



NUMBER IV 



PAGE 



The Building of the Colorado Rockies. II. RoUin T. Cham- 



berlin 225 



Notes on Principles of Oil Accumulation. Alex. W. McCoy 252 



Some Stratigraphic and Structural Features of the Pre- 



Cambrian of Northern Quebec. III. H. C. Cooke . . . 263 



A Planimeter Method for the Determination of the Percentage 



Compositions of Rocks. Albert Johannsen 276 



Geology of Florida. E. H. Sellards 286 



Recent Publications 303 



NUMBER V 



Investigation versus Propagandism. T. C. Chamberlin . . . 305 



Inequalities of Sedimentation. E. M. Kindle 339 



Some Stratigraphic and Structural Features of the Pre- 



Cambrian of Northern Quebec. IV. H. C. Cooke . . 367 



The Thurman-Wilson Fault through Southwestern Iowa and 



Its Bearings. John L. Tilton . . 383 



Reviews . 391 



NUMBER VI 



Crystallization-Differentiation in Igneous Magmas. N. L. 



Bowen 393 



The Richardton Meteorite. T. T. Quirke 431 



Pre-Cambrian Rocks of Southeast Newfoundland. A. F. Bud- 



dington 449 



Curious Erosion Features in West Tennessee Clays. Rolf A. 



Schroeder 480 



Reviews 482 



Recent Publications . . 485 



