MIDAlpha TitleTitleYearColor/BWRunning TimeFormatsAbstractTopics
1218GROUND WATER: THE HIDDEN RESERVOIRGROUND WATER: THE HIDDEN RESERVOIR1971color19 min16mm Presents a basic introduction to hydrogeology and definitions of the technical terms involved. Uses drawings and photographs to explain the hydrological cycle and shows examples of springs, caverns, sink holes and artesian wells. Warns that near-surface aquifers are in great danger of pollution due to man's naive use of fertilizers and discusses what must be done to assure a plentiful underground water supply.