DRAINAGE MODIFICATIONS AND THEIR INTER- 

 PRETATION/ 



CONTENTS. 

 Part I. Principles of drainage modification. 



(i) Relation of drainage forms to land forms. 



(2) Classes of drainage adjustments. 



Class I. Changes during the normal development of a stream. 

 Class 2. Adjustments due to rock character and geologic structure. 

 Class 3. Rearrangements caused by radial crustal movements. 



(3) Ideal cases illustrating the effect of local radial movements. 

 (a) Effects of elevation. 



{6) Effects of depression. 



(4) Law of the migration of divides. 



Part II. Criteria for determining stream modifications. 



(i) Alignment of the drainage affected by the migration of divides. 

 (a) Rectangular arrangement of the drainage lines. 

 (li) Unsymmetrical drainage basins. 



(2) Effect of the earth's rotation on drainage lines. 



(3) Modifications differ according to age. 



(a) Recent movements shown by barriers and changes of grade. 



(d) Remote movements shown by the arrangement of the minor drainage. 



{c) Very remote movements shown by the arrangement of the trunk streams. 



(4) Periodicity of stream changes. 



(5) Criteria for determining the coincidence of lines of uplift with pre-existing 

 divides. 



Part III. Appalachian drainage. 



(1) Recent movements indicated by the Muscle Shoals in the Tennessee River 

 {a) Profile of the Tennessee River. 



{d) Character of the river valley, 

 (c) Character of the stream. 



(2) Remote changes shown in the streams of the Mississippi Valley. 

 (a) Kanawha River basin. 



{/>) Big Sandy and Clinch River basins. 

 (c) River basins of Kentucky. 



(3) Streams of the Atlantic slope. 

 (a) Chattahoochee River. 



(4) Streams of the Appalachian Valley. 



(5) Very remote changes shown in some of the Appalachian rivers. 

 (a) Chattahoochee drainage line. 



(1^) Triassic areas in the same line. 



(6) Utility of the study of drainage features. 



' Published by permission of the Director of the U. S. Geological Survey. 



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