A Working Erosion Model for Schools |
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14 feet 4-inch iron pipe A. C. TRUE adjacent hills BRACKET cement classes in nature clear lake covered deforested deltas DEPARTMENT OF AGRICULTURE depressions devoid drain drainpipe effects of rainfall elevation of model ELLIS entire surface erected EROSION MODEL erosion processes EXPERIMENT STATIONS expositions farms feet long feet square fertile forest growth Forest Service forested hill front furrowed GEOLOGY GOVERNMENT PRINTING OFFICE gullies hillside hose inches land layer linear feet material model 5 feet MODEL FOR SCHOOLS Model showing mortar moss mound muddy lake nail nature study OFFICE OF EXPERIMENT OUTLET overflow paraffin physical geography piece plan of model process of erosion protected rain rear represent reservoir rubble sand section of model seep shallow showing the effects silt slant slope spray sprinkler stopcock stream beds thickly threaded.ยน TIN GUTTER tongued and grooved top soil tray twigs U. S. DEPARTMENT upper end valley washed Washington wood