250 SEA AND LAND 



in all the stages of water below mid tide the marshes present 

 a beautiful plain of vegetation the tints of which vary from 

 month to month and even from hour to hour as they re- 

 ceive or discharge their waters. Nothing in the geographic 

 world is more graceful than the curves of the creeks through 

 which the tidal waters enter and depart in their constant 

 movement. 



The variety in the character of the marine marshes which is 

 brought about by the slight changes in the amplitude of the 

 tidal swino- and other variations in the conditions of the shore is 

 singularly great and is unparalleled in the physiognomy of coral 

 reefs. Thus for each hundred miles of distance along the 

 Atlantic coast from the Straits of Belle Isle to Key West the 

 aspect of the mud flats and grass-covered plains so constantly 

 varies that anyone who was well acquainted with their peculiari- 

 ties could tell pretty nearly whereabouts he had landed on the 

 shore by the appearance of these fields. All organic life is 

 beautifully and variedly adjusted to the conditions of its environ- 

 ment, but it is doubtful if in any other zone of the organic world 

 the accommodations are more exquisitely ordered than in the 

 marshes of the ocean shore. 



It is otherwise with the harborages of our fresh water lakes. 

 In those tideless waters the action of organic life is practically 

 limited to the growth of certain rushes and sedges which spring 

 from the bottom of shallow water and gradually accumulate a 

 deposit of ordinary peat such as is so generally formed in our 

 fresh water bogs. In many cases, as, for instance, about the 

 Great Lakes of the Northwest, this accumulation of decayed 

 vegetable matter goes so far as to close a large part, if not 

 the whole, of many havens, even those which were originally 

 extensive in area. We fail, however, to find in these situa- 



