THE 



AMERICAN JOURNAL OF SCIENCE 



[FOURTH SERIES.] 



Art. XXXII. — Contributions to the Geology of the Grand 

 Canyon, Arizona. — The Geology of the Shinumo Area ; 

 by L. F. Noble. 



Part I. 

 Preface. 

 Introduction. 



Location. 



Field Work. 



Literature. 



Acknowledgments. 



Geologic Nomenclature. 

 Topography, Climate and Vegetation. 

 General Geology. 



Archean — Vishnu Schist. 

 Name. 



Distribution in the Kaibab Division. 

 Occurrence and Distribution in the Shinumo Area. 

 Lithology. 

 Origin. 



Age and Correlation. 

 Bibliography. 



Preface. 



Exposures of unaltered pre-Cambrian sediments are of great 

 interest to the geologist in any part of the world. Especially 

 is this true in the Grand Canyon of Arizona, where the cer- 

 tainty of stratigraphic position and completeness of exposure 

 are almost without a parallel, and where the spectacular nature 

 of the occurrence partakes of the stupendous and fantastic 

 scenery of that mighty gorge, from the spell of which the 

 observer is never entirely free. During a pleasure trip in the 

 Grand Canyon region in January, 1908, in company with 

 Professor H. E. Gregory of Yale and others, the writer chanced 

 to visit a hitherto undescribed exposure of these rocks on the 



Am. Jour. Scl— Fourth Series, Vol. XXIX, No. 173.— May, 1910. 

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