Rock Flour 



Fine material formed by the action of a glacier grinding 

 rocks in its base as it moves forward. 



Rodent 



An animal in the order Rodentia in the class Mammalia, 

 e.g., mouse. 



Roentgen 



(1) A unit of measurement of radiation caused by Gamma 

 rays and X-rays, very similar to Rad (q. v.). (2) Refers to 

 X-rays. 



Rogue 



To remove undesired individuals from a population to 

 prevent their reproduction. 



Rookery 



The breeding place of a group of birds or seals. 



Root Climber 



A plant that ascends by means of roots attached to a 

 support, e.g., poison ivy on the trunk of a tree. 



Root Nodule 



See Nodule. 



Rootstock 



See Rhizome. 



Root Sucker 



A sprout arising from a root. 



Root Zone 



The part of the soil occupied by roots, or subject to such 

 occupation under normal conditions, cf. Rhizosphere. 



Rotation Grazing 



The orderly alternation in the use of two or more por- 

 tions of a range or pasture. 



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