35 



deformation, should be similarly studied. The section across a 

 typical continent and ocean such as America and the Atlantic 

 shows that the unit form of continent is an arch (sagging in the 

 middle) and that of ocean a trough (with a central buckle) . These 

 great earth-features are broken into minor waves, the anticlines 

 and synclines of the geologist, of every size and grade, but all 

 composed of arch and trough like the letter S, or Hogarth's ' line 

 of beauty and grace.' Each wave has an arch limb and a trough 

 limb divided by a septum, and the steepest septum, as in a wave 

 at sea, is on the advancing side of the crest. It is this septum 

 which undergoes the greatest amount of twisting and distortion 

 as the fold grows until all three parts are crushed together into a 

 single mass and the fold is dead, but it has given its life to the 

 thickening and strengthening of the weak part of the earth's crust 

 at which it originated. The *" period of greatest effective energy 

 and most rapid movement must be that of middle life," when the 

 septum is vertical. 



I. Geographical Relations. 



Applying these deductions to earth features, the steeper, 

 or ocean, septa of the great North American folds show 

 greater crumpling and metamorphism than do those on the 

 Mississippi sides. Of the two folds, that on the Pacific 

 side has a steeper septum than that on the Atlantic side, it is 

 ' ablaze with volcanoes, or creeping with earthquakes, 'f and has 

 in front of it the great Pacific ' deep.' Similarly in the central 

 buckle of the Atlantic trough the volcanic islands are septal in 

 position. 



A like feature on a still grander scale is the ' land hemisphere ' 

 with its ' central sag,' the Atlantic, opposite to which is the great 

 trough of the Pacific Ocean with its median buckle the foundation 

 of the oceanic islands of the central Pacific. Since this fold is 

 endless and returns upon itself its septum must likewise be 

 endless ; it is the ' Volcanic Girdle of the Pacific,' the ' Terrestrial 

 Ring of Fire.' 



Thus the J" wave-like surface of the earth of the present day 

 reflects .... the wave-like arrangement of the geological forma- 

 tions below." " The physiognomy of the face of our globe is an 

 unerring index of the solid personality beneath." 



But as the result of other tangential stresses " the simple 

 fold becomes a folded fold, and the compound septum twists not 

 only vertically but laterally." It is this which accounts for domes 

 and basins, for the sweep of island festoons, and " for the detailed 

 disposition of our lands and our waters, for our present coastal 

 forms, for the direction, length, and disposition of our mountain 



* 48. p. 703- t 48, p. 704- J 48, P- 705- 48. P- 706. 



