This short was sponsored by either an oil company or mining operation to produce an educational short about geology. The Hubleys did a marvelous job. The veteran character actor Jack Warden is the voice of "Rocko", our underground tour guide, explaining terms such as igneous and sedimentary to the audience. I first saw this in a high school geology class. It was included in The Cosmic Eye and is available on DVD and is worth the effort to get. Recommended.