§ Mr. Penhaligonasked the Secretary of State for Energy if he will list the steps 14W workable by opencast methods total some 200 million tons. Prospecting for coal is a continuing process and during each of the last 10 years the Open Cast Executive of the NCB has proved more coal than has been produced from opencast sites. In addition to these fully and partly proved reserves it is estimated that further potential reserves are at least equal to those fully or partly proved.