Traces the history of various theories about Mars that were derived through direct observation. (MLH)

This is the first article of a two-part series on how research can help reduce the hazards of earthquakes. It deals with attempts to predict quakes so that people can get out of the way. (Author/HM)

Describes the physical aspects of Mars, including old and new theories. Discusses the proposed landing sites of Viking. (MLH)

Reviews current ideas and research findings related to the flow patterns of mantle rocks. Highlights the components of the two-layer convection and whole-mantle models of mantle flow. Proposes that mantle flow is the key to understanding how the earth has cooled and chemically evolved. (ML)