THE 
MOURNAL OF GEOLOGY 
NOVEMBER-DECEMBER, 10912 
THE BANNOCK OVERTHRUST 
A MAJOR FAULT IN SOUTHEASTERN IDAHO AND NORTE- - 
EASTERN UTAH 
R. W. RICHARDS anp G. R. MANSFIELD 
INTRODUCTION 
EARLIER WoRK 
STRATIGRAPHY 
Outline 
Phosphoria Formation 
Wells Formation 
Upper Mississippian Limestone 
BANNOCK FAULT 
Georgetown Fault 
John Grays Lake and Blackfoot Faults 
Montpelier Fault 
Swan Lake Fault 
West Bear Lake Fault 
Faults near Laketown and Woodruff, Utah 
Magnitude of the Bannock Fault 
Age of the Bannock Fault 
Deformation of Fault Plane 
Parallel Associated Thrusts 
RELATION OF BANNOCK THRUST TO PARALLEL THRUSTS 
BIBLIOGRAPHY 
INTRODUCTION 
In the course of a detailed geologic examination of portions 
of the Phosphate Reserve in southeastern Idaho during ro11 and 
1912, the writers have had an opportunity to study an overthrust 
Vol. XX, No. 8 681 
