XLbc S^ournal of (3eolog^ 



Vol. XXII CONTENTS FOR MAY-JUNE J9J4 No. 4 



THE STRENGTH OF THE EARTH'S CRUST. IV. HETEROGENEITY AND RIGIDITY OF THE CRUST 



AS MEASURED BY DEPARTURES FROM ISOSTASY Joseph Barrell 289 



DIASTROPHISM AND THE FORMATIVE PROCESSES. VII. PERIODICITY OF PALEOZOIC OROGENIC 



MOVEMENTS Rollin T. Chamberlin 315 



ON THE RELATIONS OF THE GREAT MARLBOROUGH CONGLOMERATE TO THE UNDERLYING 



FORMATIONS IN THE MIDDLE CLARENCE VALLEY, NEW ZEALAND - - - - C. A. CoTtON 346 



THE OSTEOLOGY OF SOME AMERICAN PERMIAN VERTEBRATES S. W. Williston 364 



STUDIES FOR STUDENTS: A CLASSIFICATION OF COMMON SEDIMENTS AND SOME CRITERIA FOR 



IDENTIFICATION OF THE VARIOUS CLASSES ------- Arthur C. Trowbridge 420 



PETROLOGICAL ABSTRACTS AND REVIEWS 437 



REVIEWS - 440 



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