VOLUME XXXI NUMBER 8 



THE 



JOURNAL OF GEOLOGY 



November-December ig2J 



THE CHANNELED SCABLANDS OF THE 

 COLUMBIA PLATEAU 



J HARLEN BRETZ 



University of Chicago 



OUTLINE 



Definition of "Scabland" 



Physiographic Relations of the Channeled Scablands 



Generalized Statement of the Origin of the Channeled Scablands 



The Basalt Plain, North of the Scablands and the Mature Topography 



The Mature Topography 



Details of a Scabland Surface 



Altitudes and Giudients of the Scabland Tracts 



Depth of Glacial Stream Erosion in the Scablands 



Criteria 



Instances 

 Volume of the Glacial Streams 

 Deposits Made by the Glacial Streams 

 Depths of Snake and Columbia Valleys during the Epoch 

 The Glaciation 



DEFINITION OF " SCABLAND " 



The terms "scabland" and "scabrock" are used in the Pacific 

 Northwest to describe areas where denudation has removed or 

 prevented the accumulation of a mantle of soil, and the underlying 

 rock is exposed or covered largely with its own coarse, angular debris. 

 The largest areas of scabland are on the Columbia Plateau in Wash- 



617 



