154 PROCEEDINGS OF THE AMERICAN ACADEMY. 



PART I. INITIAL FORMS. 



1. The Geographic Cycle. 



Systematic Sequence of Forms. — Before the consideration of the initial 

 forms themselves is undertaken, the position of the initial stage in relation 

 to geographic cycles of development must be clearly understood. Conse- 

 quently at the outset some of the general facts of cycles will be discussed 

 in their bearing upon the problem of stages in the development of shore- 

 lines, and particularly as regards the initial or first stage of a cycle. 



In this paper many facts from different sources are brought together, 

 and the attempt is made to show some of the laws of coastal development. 

 After the inductive study of coast forms upon the better mapped areas of 

 the world had been made, and the deductive scheme of development 

 worked out, gaps in the scheme were found which are not filled by ex- 

 amples. This lack of facts to fit ideal cases may be because they do not 

 exist upon our small earth, or because they have not been reported, as 

 well as on account of a defective scheme. By showing w here such gaps 

 in our theoretical scheme of development occur at present, the eyes of 

 future field workers may be sharpened to look for the expectable facts. 



Succession on Land. — Land forms go progressively through a series of 

 successive stages of development, to which have been applied names taken 

 from various stages of life, thus suggesting that forms as seen to-day 

 began as something else, and will as time advances become systematically 

 still further developed. Stages of the cycle follow one another from birth 

 to death in the ideal case, where the land stands still long enough for the 

 completed development. The initial stage, or birth, is succeeded in turn 

 by infancy, youth, adolescence, maturity, past-maturity, old age, and 

 finally by death. 



A new cycle is inaugurated by each oscillation of any considerable 

 amount, minor changes of level being included as epicycles, or divisions 

 of a cycle. Land forms advance successively from infancy toward old 

 age in each cycle, while any stage of development may be arrested by 

 elevation or depression of the land and a second cycle begun. An essential 

 conception is that a region will be finally reduced to a peneplain if the 

 baselevelling action of the streams, and the other forces of subaerial 

 degradation, be allowed to continue long enough to reduce the land 

 forms to extreme old age. Insequent, consequent, subsequent, and ob- 

 sequent streams all play their part in the development of the land forms, 

 captures of one stream by another follow unequal chances, while super- 



