A boy and his dog take a wondrous trip under the earth's crust and through the geological eras of time, introducing children to geology in the form of a musical fantasy.
| Actor | Role |
|---|---|
 Jack WardenRocco (voice) | Rocco (voice) |
| RRay HubleyAdam (voice) | Adam (voice) |
 Maureen StapletonMother (voice) | Mother (voice) |
 Morris CarnovskyEarl of Limestone (voice) | Earl of Limestone (voice) |
 Phil LeedsPre-Cambrian Rocks (voice) | Pre-Cambrian Rocks (voice) |
 Harry EdisonUncle Igneous (voice) | Uncle Igneous (voice) |
| DDon ElliottAunt Sedimentary (voice) | Aunt Sedimentary (voice) |
| RRuth PriceCousin Metamorphic (voice) | Cousin Metamorphic (voice) |