VOLUME XXXI NUMBER 6 



THE 



JOURNAL OF GEOLOGY 



September-October ig2J 



SUMMARY OF THE GEOLOGY OF THE BEARTOOTH 

 MOUNTAINS, MONTANA^ 



ARTHUR BEVAN 



University of Illinois, Urbana, 111. 



OUTLINE 



Location and Extent of the Range 

 Salient Topographic Features 



The Plains-ward Front 



The Sub-summit Plateau ' 



The Summit Plateau 

 Stratigraphy 



The Pre-Cambrian Core 



Sedimentary Formations 



Tertiary Igneous Rocks 



Terrace Gravels 



Glacial Drift 

 Structure 



General Form of the Range 



The Beartooth Overthrust 



The Clark Fork Fault (?) 

 History of the Range 



Antecedent Conditions 



Early Tertiary Orogeny 



Epochs of Peneplanation 



Quaternary Events 

 Acknowledgments 



^ An abridgment of a thesis submitted in partial fulfilment of the requirements for 

 the degree of Doctor of Philosophy at the University of Chicago, 1921. 



Presented in condensed form at the Chicago meeting of the Geological Society of 

 America, December 1920. 



441 



