WAVE-LIKE PROGRESS OF AN EPEIROGENIC 

 UPLIFT/ 



To the ancient Greeks the word epeiros, specially applied to 

 the land lying next north, signified also, in general, any mainland 

 or continental area, as contrasted with islands or their own 

 peninsular country. From this word Gilbert has recently sup- 

 plied to our science the terms epeiroge^iy and epeirogenic, to desig- 

 nate the broad movements of uplift and subsidence which affect 

 the whole or large parts of continents and of the oceanic basins.^ 

 Previously the correlative terms orogeny and orogenic had come 

 into use, denoting the process of formation of mountain ranges 

 by folds, faults, upthrusts and overthrusts, affecting compara- 

 tively narrow belts and lifting them in great ridges, while the 

 epeirogenic movements of the earth's crust produce and maintain 

 the continental plateaus and the broad depressions which are 

 covered by the sea. 



During the closing part of the Tertiary era and the present 

 Quaternary or Psychozoic era, both epeirogenic and orogenic 

 changes have been in progress on many portions of the earth, 

 and on a scale of grandeur probably never before surpassed. 

 Where these movements have raised continental regions or. 

 mountain districts to much greater altitudes than they now 

 retain, if they were situated within the range of prevailing air 

 currents abundantly laden with moisture and were at latitudes 

 so far from the equator that the precipitation was chiefly snow 

 throughout the year, they became for a time enveloped by ice- 

 sheets, which have left the surface strewn with glacial and modi- 

 fied drift. Fjords, and now submarine continuations of river 



' Presented before the World's Congress on Geology, auxiliary with the Columbian 

 Exposition, Chicago, August 25, 1893. This paper is an attempt to answer, by a 

 definite example, a portion of the inquiries in an editorial of the Journal of 

 Geology, Vol. i, page 298, April-May, 1893. 



^"Lake Bonneville," Monograph I., U. S. Geological Survey, 1890, p. 340. 



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