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National Geographic Magazine.
Part third. General conception of the history of a river.
- The complete cycle of river life: youth, adolescence, maturity and old age.
- Mutual adjustment of river courses.
- Terminology of rivers changed by adjustment.
- Examples of adjustments.
- Revival of rivers by elevation and drowning by depression.
- Opportunity for new adjustments with revival.
- Antecedent and superimposed rivers.
- Simple, compound, composite and complex rivers.
Part fourth. The development of the rivers of Pennsylvania.
- Means of distinguishing between antecedent and adjusted consequent rivers.
- Postulates of the argument.
- Constructional Permian topography and consequent drainage.
- The Jura mountains homologous with the Permian Alleghanies.
- Development and adjustment of the Permian drainage.
- Lateral water-gaps near the apex of synclinal ridges.
- Departure of the Juniata from the Juniata-Catawissa syncline.
- Avoidance of the Broad Top basin by the Juniata headwaters.
- Reversal of larger rivers to southeast courses.
- Capture of the Anthracite headwaters by the growing Susquehanna.
- Present outward drainage of the Anthracite basins.
- Homologies of the Susquehanna and Juniata.
- Superimposition of the Susquehanna on two synclinal ridges.
- Evidence of superimposition in the Susquehanna tributaries.
- Events of the Tertiary cycle.
- Tertiary adjustment of the Juniata on the Medina anticlines.
- Migration of the Atlantic-Ohio divide.
- Other examples of adjustments.
- Events of the Quaternary cycle.
- Doubtful cases.
- Complicated history of our actual rivers.
- Provisional conclusions.
Part first. Introductory.
1. Plan of work here proposed.—No one now regards a river and its valley as ready-made features of the earth's surface. All are convinced that rivers have come to be what they are by slow processes of natural development, in which every peculiarity of river-course and valley-form has its appropriate cause. Being
