Filter Strip 



A strip of permanent vegetation sufficiently wide and 

 dense above a farm pond, diversion terrace, etc., so it will 

 retard run-off and cause deposition, thus preventing silting 

 in the water or structure below. 



Fine-textured Soil 



A soil that consists mainly of silt and clay. 



Fiord (Fjord) 



A narrow, often long and deep inlet of the sea as in the 

 coasts of Norway and Alaska, very likely formed by glaciers. 



Firebreak 



A strip of land from which inflammable materials have 

 been removed in order to check or stop a creeping or 

 running fire. 



Fire Control Line 



The line along which efforts are made to stop the advance 

 of a fire or from which to start to backfire. 



Fire Hazard 



The risk of probabilities that a fire may start because 

 of the inflammability of materials under the prevailing 

 climatic conditions. 



Firn 



See N4v4. 



First Bottom 



The Flood plain that is most immediate to a stream, or 

 at the lowest elevation above a stream, consequently some 

 are frequently flooded. 



Firth 



A long, narrow arm of the sea or lower portion of an 

 estuary, especially in Scotland. 



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