Float 



Floating platform or other device moored to bottom of a waterway. 



Flood tide 



Period between low water and the succeeding high water; rising tide. 



Food chain 



Dependence of a series of organisms, one upon another, for food; begins 

 with plants and ends with largest carnivores. 



Forb 



Herb other than grass. 



Foreshore 



Part of the shore lying between crest of seaward berrr and ordinary low 

 water mark. 



Freeboard 



Distance between waterline and top deck of a structure or vessel. 



Fringe marsh 



A narrow wetland at the edge of a body of water. 



Gabion 



Hollow cylinder filled with earth; see revetment. 



Grass flats 



Flat areas alternately covered and uncovered by tidal action which sup- 

 port extensive growths of grasslike vegetation. 



Grave I 



Loose, rounded fragments cf rock, C.75 to 3in (1.8 to 7.6cm) diameter. 



Groin, groyne (Bristish) 



A rigid structure built at an angle (usually perpendicular) from the shore 

 to protect it from erosion or to trap sand. A groin may be further defined 

 as permeable or impermeable depending on whether or not it is designed to 

 pass sand through it. 



Groin field (also groin system) 



Series of groins spaced along the shoreline acting together to protect a 

 section of beach. 



Gribbles 



Small marine isopod crustacean (UmruDria spp.) that destroys submerged 

 timber. 



Gulf 



Large embayment, entrance generally wider than length. 



Habit 



Characteristic mode of growth or appearance. 



148 



