382 A. C. LANE STUDIES OF GRAIX OF IGXEOUS INTKUSIVES 



Plate 56. — Curves of Cooling — Effective Contact Zone Broad 



The temperatures of an igneous sheet with a contact zone of equal width are 

 indicated by ordinates, the lapse of time by the abscissas measured from the be- 

 ginning at the right. The curves are temperature curves for various distances 

 from the margin of the zone affected. The full lines represent temperatures of 

 the heated masses, the lines in dashes temperatures in the contact zone. The 

 scales are the same as in plate 54. 



