viii CONTENTS OF VOLUME XVIII 



NUMBER VIII 



PAGE 



A Central African Glacier of Triassic Age. Sydney H. Ball and 



Millard K. Shaler 68i 



The Puerco and Torrejon Formations of the Nacimiento Group. 



James H. Gardner 702 



A New Erosion Cycle in the Grand Canyon District, Arizona. 



H. H. Robinson 742 



Editorial: Are there Line Fences in Science? T. C. C. . . 764 



