Recent work in the extreme southeastern part of Madagascar suggests that the Androyen system be subdivided on the basis of stratigraphic rather than metamorphic zones. The Anosyen granites and their train of charnockites were developed at variable levels within the upper pyroxenite series which is distinctly layered. These upper series contain thorium deposits (thorianite in the phroxenites, monazite in the granites); the Anosyen granitization and thorium concentration are related to the Eocambrian orogeny 485 million years ago.