Abstract

This chapter explores the various hypotheses put forward for the formation of the Martian dichotomy, the topographic difference between the northern lowlands and the southern highlands of the planet. Among the various hypotheses, the Southern Polar Giant Impact (SPGI) was the only one validated with the discovery of twelve volcanic alignments as predicted by the 3D model. Furthermore, this hypothesis is the only one that matches both astronomical and geophysical data available in the literature and all the requirements to be seriously considered as a theory. The various volcanic centres of Mars, including the vast majority being part of the alignments, are described with full detail in this chapter.