The core portion of this trial unit prepared by the Australian Science Education Project provides an introduction to the structure of the earth, volcanic activity, the types of igneous rocks, earthquakes, and seismology, with an emphasis on the techniques of inference used to relate external evidence to internal structure. The optional activities provide the opportunity to obtain more extensive information on volcanoes, the relationship between formation and structure of igneous rocks, the rock cycle, continental drift, magnetism and the earth, the location of earthquakes by the use of seismographic evidence, geological mapping and the inference of subsurface structure, and the use of igneous rocks. Students are provided with extensive second-hand data, and with instructions for the conduct of a number of simulations of geological phenomena. There is a separate workbook with spaces for the written record of the student's work, and a question booklet containing diagnostic test to be used after the core. The teachers' guide prepared for the unit is not included in this package. (AL)