386 BOARD OF AGRICULTURE. [Pub. Doc. 



tion of the soft muck which is so characteristic a feature ic 

 our fresh- water bogs. 



As these marine marshes are at many points in process of 

 growth, the manner in which they are formed can readily be 

 observed. The first step in this process consists in the 

 shoaling of the water next the shore by the deposition of 

 sediments borne to the locality by the action of the tide or 

 washed in from the shore, to which is added the material 

 derived from the animals and plants which live and die upon 

 the bottom. Below the level of low tide the accumulation of 

 these sediments or their retention in places which are visited 

 by the currents which generally sweep our shores is in most 

 places greatly favored by the growth of the plant known as 

 eel grass, a singular flowering species which is able to main- 

 tain itself beneath the level of the water. The long, slender 

 leaves of this species, growing as they do thickly set upon 

 the bottom, form an admirable network in which the silt 

 swept to and fro by the tide readily comes to rest. When 

 by the process of accumulation the eel-grass flats are lifted 

 to near the surface of low water, they are abandoned by this 

 plant and are seized upon by various species of seaweeds 

 which favor the further accumulation of sediment. When 

 the muddy deposits have attained to a level a little above low- 

 tide mark, the surface is prepared for the occupation of sev- 

 eral species of true grasses, which build the characteristic 

 marine marsh. 



Beginning next the shore, these plants soon form a fringe 

 of salt-marsh grass land, which quickly grows upward 

 through the accumulation of dead roots and stems, the waste 

 swept in by the tide, and tangled amid the vegetation and 

 the coincident development of many animals which dwell 

 amid the herbage, until the meadow attains very nearly the 

 level of ordinary high tide, after which it ceases to grow 

 upward. The outward horizontal growth of the sheet 

 goes on, however, with conspicuous rapidity. In favorable 

 positions this front of entangled roots and stems, so tough 

 that it can withstand the blows of considerable waves, 

 advances over the mud flats at the rate of three or four 

 inches a year. As the surface of the marsh is thus enlarged, 

 the sea waters which visit it at each flood tide gather into 



