2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8o 



Sciences for the financial assistance which made this investigation 

 possible. The loan of type specimens by Dr. R. S. Lull, Peabody 

 Museum of Natural History, Yale University, Dr. Witmer Stone of 

 the Philadelphia Academy of Natural Sciences, and Dr. John J. 

 Tilton of the University of West Virginia, vi^as of the greatest assis- 

 tance in the study of the material. I wish also to express my apprecia- 

 tion for the help and many courtesies rendered by the various members 

 of the Park organization. To Superintendent J. R. Eakin I am 

 deeply indebted for the use of equipment, and assistance of person- 

 nel ; to Mr. E. T. Scoyen, chief ranger, for the detail of ranger 

 assistants, and for his personal interest on many occasions : and to 

 Mr. G. E. Sturdevant, ranger naturalist, whose efficient help and 

 familiarity with fossil localities contributed so much to the successful 

 outcome of the expedition. Mr. Arthur Metszer, who acted as my 

 assistant on this as well as on my previous trip, furnished intelligent 

 and industrious help in making the collections, and throughout the 

 work exhibited a personal interest in the success of the expedition 

 second only to my own, 



GEOLOGICAL OCCURRENCE OF FOSSIL TRACKS 



In the Grand Canyon National Park, the tracks of extinct animals 

 occur in three distinct geological formations which, named in descend- 

 ing order, are the Coconino, Hermit, and Supai. Credit for the dis- 

 covery of fossil tracks in the Grand Canyon goes to Professor Charles 

 Schuchert of Yale University, who, in 1915, while making a study 

 of the geology of the Hermit Trail section, noted the presence of 

 tracks in all three formations.^ After reading his account of their 

 occurrence it is quite apparent that he was unaware at the time of 

 their great abundance and variety. Fossil tracks occur in considerable 

 abundance in all of these formations and at several levels. These 

 later investigations show that in the great variety of footprints found 

 and in the perfection of their preservation, there are few localities 

 that outrank this one. It is further unique in being probably the only 

 place in the world where fossil tracks of three successive faunas may 

 be found in one nearly vertical geological section, separated by such 

 great geological intervals. 



Tracks occur throughout a zone 130 feet thick in the lower part 

 of the Coconino (see fig. i), the bottom 20 feet being barren of 

 impressions. In the Hermit shale, tracks, plants, and insects were 

 found in the hollows or troughs eroded in the top of the underlying 



\\mer. Journ. Sci., Ser. 4. Vol. 45, 1918, pp. 350, 354, and 357. 



