Describes a computer simulation called "Supercontinent Aggregation and Dispersal" designed to model the interplay between the movement of the continents and the flow patterns of rock in the mantle. Discusses the strengths and weaknesses of the program in relation to the effects of continents on the mantle. (CW)

Describes a computer program written in Microsoft BASIC for use on personal computers to calculate travel times of refracted waves in layered structures with arbitrary dipping interfaces. Exercises for student use are given to illustrate some of the basic properties of reversed refraction travel time graphs. (TW)