648 ELIOT BLACKW ELDER 



the north the deformation may be traced through the Oregon Coast 

 Range to the Olympic Mountains of Washington, thence through 

 the coastal islands of British Columbia, to the southern Alaska 

 coast, and on into the Aleutian chain. To the south the same 

 deformation is reflected in the tilted and more or less disturbed 

 Eocene beds of Lower California. Beginning in southwestern 

 Mexico, a belt of complexly folded and faulted rocks with volcanoes 

 extends through Honduras and other Central American states, 

 through the West Indian islands to Venezuela. These folds involve 

 Eocene, Oligocene, and even Miocene strata, but are unconformably 

 overlapped by the undisturbed Pliocene. Eastward and north- 

 ward the effects of the Antillean disturbance wane into gentle folds 

 and finally into mere warping, accompanied by normal faults and 

 volcanic structures. Decided folding of early Tertiary strata ex- 

 tends as far east as southwestern Nevada, the Blue Mountains of 

 Oregon, the Cascade Range and Okanagan regions of Washington, 

 at least the western part of the Eraser River basin of British 

 Columbia, and the upper Yukon valley. In Alaska it affected the 

 Kuskokwim Mountains and Nunivak Island, but not the Mt. 

 Wrangell district or the region north of the Yukon River. Even 

 as far east as the Rocky Mountain states of Wyoming, Colorado, 

 and Montana, the Eocene and Oligocene strata are locally somewhat 

 tilted and broken by normal faults, suggesting that the Antillean 

 disturbance made itself felt in a mild way as far east as the edge 

 of the Great Plains. Eastern United States suffered no folding 

 but there was some warping, especially in Florida and the Gulf 

 states. 



By comparison with the Nevadian and Laramide disturbances, 

 it will be seen that the Antillean orogeny affected an area as large 

 as, or even larger than, the Nevadian, and again the strongest fold- 

 ing is found nearest the Pacific coast. Almost throughout the 

 range of the Miocene disturbance, whether mild or severe, volcanoes 

 broke forth and scattered their lavas and fragmental deposits far 

 and wide. In that respect the epoch may have exceeded even the 

 Laramide orogeny. Batholiths of the Antillean epoch are reported 

 from the Cascade Mountains of Washington and British Columbia; 

 they are probably the youngest known. 



