CONTENTS OF VOLUME XX 
NUMBER I 
Tue PERMO-CARBONIFEROUS OF NORTHERN NEw Mexico. S. W. 
Williston and E. C. Case 
ON THE DISTRIBUTION OF LOWER TRIASSIC FAUNAS. James Perrin 
Smith 
PANTYLUS CoRDATUS CoPpE. Maurice G. Mehl 
NOTES ON TERTIARY DeEposits NEAR COALINGA OIL FIELD AND THEIR 
STRATIGRAPHIC RELATIONS WITH THE UPPER CRETACEOUS. E. T. 
Dumble 
Kauri Gum MINING IN NEw ZEALAND. R.A. F. Penrose, Jr. 
PRELIMINARY NOTES ON SOME IGNEOUS ROCKS OF JAPAN. V. S. Koézu 
GRAVEL AS A RESISTANT Rock. Sidney Paige 
SOME OBSERVATIONS AND EXPERIMENTS ON JOINT PLANES. I. Pearl 
Sheldon 
PETROLOGICAL ABSTRACTS AND REVIEWS . 
REVIEWS 
NUMBER It 
AN EXPERIMENTAL CONTRIBUTION TO THE QUESTION OF THE DEPTH 
OF THE ZONE OF FLOW IN THE EArRTH’sS Crust. Frank D. Adams 
ON THE LIMITING STRENGTH OF ROCKS UNDER CONDITIONS OF STRESS 
EXISTING IN THE Eartu’s INTERIOR. Louis Vessot King 
AN OLp EROSION SURFACE IN IDAHO: Its AGE AND VALUE AS A DATUM 
PLANE. Joseph B. Umpleby 
EuceN Hussak. Miguel A. Lisboa 
THE PETROGRAPHIC CHARACTER OF OHIO SANDS WITH RELATION TO 
THEIR ORIGIN. D. Dale Condit . 
SOME OBSERVATIONS AND EXPERIMENTS ON JOINT PLANES. II. Pearl 
Sheldon 
REVIEWS 
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