BULL. GEOL. SOC. AM. 



VOL. 31, 1919, PL. 9 



Scale 



f Temperat 

 I Pressure 



URE Units IOO'C 

 Units IOOOO Lbs 



D Inch 



DIAGRAM OF COMPRESSION AND THERMAL EXPANSION OF ROCK 

 BETWEEN THE SURFACE AND A DEPTH OF 40 MILES 



