Using many colour illustrations and Viking images not previously available to the general public, the author deals separately with different regions of Mars - such as the ancient cratered highlands, the volcanic plains and the polar regions. He then demonstrates how the development of each is part of a gradual evolutionary process that included an early bombardment of the ancient crust, subsequent development of rivers and streams (even shallow oceans), widespread volcanism, periglacial activity, and Martian winds. The book concludes with a summary of the planet's geological development as scientists now believe it to have occurred.