An extensive and lofty chain of mountains in North America, belonging to the Cordillera system, and forming the eastern buttress of the great Pacific Highlands, of which the Sierra Nevada and Cascade Mountains form the western buttress, stretching in rugged lines of almost naked rock, interspersed with fertile valleys, from New Mexico through Canada to the Arctic Ocean, broken only by a wonderfully beautiful tract of elevated plateau in southern Wyoming, over which passes the Union Pacific Railroad; reaches its greatest height in Colorado (Gray's Peak, 14,341 ft.); gold, silver, &c., are found abundantly.