SOME OBSERVATIONS AND EXPERIMENTS ON JOINT 
PLANES? 
PEARL SHELDON 
INTRODUCTION 
Folding 
Faulting 
OBSERVATIONAL WORK 
Joint Planes 
Fall Creek Joint Planes 
Joints of the Entire Region 
Strike Joints 
Effect of the Rock Character 
Hade of the Strike Joints 
Dip Joints 
Hade of the Dip Joints 
Minor Joints 
Influence of Joints on Topography 
II 
EXPERIMENTAL WORK 
Network of Cracks 
Finest Cracks 
DEDUCTIONS 
Age of the Joint Planes 
Strike Joints 
Dip Joints 
Evidence of the Dikes 
Cause of the Joint Planes 
Tension Theory 
Earthquake Theory 
Torsion Theory 
Shear Theory 
* This was done as part work for a Ph.D. degree at Cornell University. Acknowl- 
edgments are due to Professors R. S. Tarr and G. D. Harris for information and 
criticism. 
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