CONTENTS. 
Page. 
Outline of principal results 7 
Chapter I. Introduction -. 11 
Purpose of the investigation 11 
Previous work 12 
Acknowledgments 13 
Chapter II. Geography, topography, and general geology 14 
Geography and topography 14 
General geology 16 
Faults, joints, and fissures 18 
Sequence of geologic events 21 
Development of topography 22 
Chapter III. Sedimentary formations 24 
Carboniferous system 24 
Homestake limestone 24 
Distribution 24 
Character 25 
Contact metamorphism of limestone by andesite laccoliths .... 25 
Phases of alteration 25 
Introduction of ore 27 
Normal contact phase 27 
Exceptional contact phases 33 
General result of alteration 34 
Changes in density and volume during contact metamorphism . 34 
Physical conditions of contact metamorphism 36 
Sandy phase of limestone 36 
Fossils 37 
Structural relations and thickness 37 
Cretaceous system 37 
Pinto sandstone 37 
Distribution 37 
Character 38 
Contact metamorphism by laccoliths 40 
Fossils 40 
Structural relations and thickness 40 
Tertiary system (Eocene) 41 
Claron limestone 41 
Distribution 41 
Character 42 
Fossils 43 
Structural relations and thickness 43 
Contact metamorphism by effusives 43 
3 
