THE CRETACEOUS PERIOD. 



167 



the withdrawal of the sea from its epicontinental extension. We have avoided 

 calling the emergence of the land an uplift on this account. It is not, as we 

 conceive, a mere matter of relativity. The initial act lies with the ocean bot- 

 tom, and the water seconds this by an actual withdrawal. 



But this is not thought to complete the sequence of events. The continental 

 platform is warped in its various parts as it follows the ocean basins in sinking. 

 This seems to have two phases at least. The one is expressed in the facts already 



Fig. 406. — Map and section showing relations of igneous rock to the Cretaceous for- 

 mations in the Crazy Mountains of Montana. The section is along the line AB 

 of the map. Klv, Livingston formation; di, diorite; gr, granite. The especial 

 feature of the map is the extraordinary number of dikes radiating from the cen- 

 tral intrusion, di. The shaded area about di represents the zone of contact meta- 

 morphism about the intrusion. Length of section about 20 miles, (Livingston 

 and Little Belt, Mont., folios, U. S. Geol. Surv.) 



