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Subsidence will effect various zones of .the overburden: The over- <br />• burden zone closest to the coal seam will experience the greatest and <br />most pernianent damage. Random re-orientation of the strata may take <br />place in this zone. In all other overburden zones, the effects of sub- <br />sidence are transitory and little, if any, permanent or lasting damage <br />is expected. <br />The volume of overburden affected by mining is a function of the angle <br />of draw. Mhen mining a nearly flat coal seam. the angles of draw with <br />respect to the ribsides of the mined out area are symetrical. However, <br /> <br />16-~ ~ <br />(Revision JUNE 1982) <br />