XLbc S^ournal of 0eoloQiP 



Vol. XXII CONTENTS FOR OCTOBER-NOVEMBER i9H No. 7 



A SUMMARY OF THE OROGENIC EPOCHS IN THE GEOLOGIC HISTORY OF NORTH AMERICA 



ElIOX BlACKrWELDER 633 



THE STRENGTH OF THE EARTH'S CRUST. VI. RELATIONS OF ISOSTATIC MOVEMENTS TO A SPHERE 



OF WEAKNESS— THE ASTHENOSPHERE ---------- Joseph Barrell 655 



A COMPARISON OF THE CCEUR D'ALENE MONZONITE WITH OTHER PLUTONIC ROCKS OF IDAHO 



C. A. Stewart 684 



A GRAPHIC METHOD OF REPRESENTING THE CHEMICAL RELATIONS OF A PETROGRAPHIC PROVINCE 



Frank D. Adams 689 



THE MODE OF FORMATION OF CERTAIN GNEISSES IN THE HIGHLANDS OF NEW JERSEY (Concluded) 



ClARElteE N. Fenner 694 



A COMPARISON OF THE CAMBRIAN AND ORDOVICIAN RIPPLE-MARKS FOUND AT OTTAWA, CANADA 



E. M. Kindle 703 



NEW AND LITTLE-KNOWN INSECTS FROM THE MIOCENE OF FLORISSANT, COLORADO 



T. D. A. Cockerell 714 



PETROLOGICAL ABSTRACTS AND REVIEWS ----- 725 



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