Closed captioned for the hearing impaired. The Corporation, 1982. Title from data sheet. Title from cassette label. Originally broadcast on PBS in 1986.
Scientists examine plate tectonics, one of the most important discoveries of the twentieth century.
Originally broadcast as a National Geographic explorer presentation in 1989. Huntsville, TX Vestron Video, distributed by Educational Video Network, 1990. Produced by WGBH for the Nova television series. Educational Video Network, c1979. Revised version of the motion picture issued in 1971 under the same title.