Contents of Volume XXIV 



NUMBER I 



PAGE 



The Acadian Triassic. Part I. Sidney Powers i 



Average Regional Slope, a Criterion for the Subdivision of Old 



Erosion Surfaces. Leopold Reinecke 27 



Caimanoidea Visheri, a New Crocodilian from the Oligocene of 



South Dakota. Maurice G. Mehl 47 



On the Structure and Classification of the Stromatoporoidea. 



M. Heinrich , 57 



The Physiography of Mexico. Warren N. Thayer .... 61 



Reviews 95 



NUMBER II 

 The Acadian Triassic. Part II. Sidney Powers .... 105 



Notes on Ripple Marks. J. A. Udden . . . . . . . .123 



Pyrophyllitization, Pinitization, and Silicification of Rocks 



around Conception Bay, Newfoundland. A. F. Buddington . 130 

 The Origin of Red Beds. A Study of the Conditions of Origin 



OF THE PeRMOCARBONTFEROUS AND TRIASSIC RED BEDS OF THE 



Western United States. Part I. C. W. Tomlinson . . 153 



Studies in Hydrothermal Alteration. I. E. A. Stephenson . . 180 

 Zonal Weathering of a Hornblende Gabbro. Albert D. Brokaw 



and Leon P. Smith 200 



Reviews 206 



NUMBER III 



Orville A. Derby. John C. Branner 209 



Types of Prismatic Structure in Igneous Rocks. Robert B. Sos- 



man 215 



Ellipsoidal Lavas in the Glacier National Park, Montana. 



Lancaster D. Burling 235 



v 



