Seismic studies indicate the interior of the Earth consists of three parts: a hot metallic core, a dense rocky mantle, and a thin low-density crust. The central part of the core is solid, but the outer part of the core is evidently liquid. In geology, a "dome" is a circular or elliptical upfold type of structural deformation; a "rise" is a long and broad elevation rising gently from its surroundings; "mantle plumes" are thin vertical conduits of molten rock material from the core-mantle boundary to the crust. The term "lithosphere" refers to the outer layer of the Earth, comprising the crust and upper mantle, and extending to a depth of 50 to 70 kilometers. All of these terms have applicat- ions in the study of the geology of other planets. .... ... Phillips and Hansen (2 installations, US) review extant data concerning the geology of crustal plateaus and volcanic rises on Venus, and present a model for their formation, and a model of the thermal evolution of the lithosphere of Venus. The authors suggest that crustal plateaus and volcanic rises on Venus formed as a result of the interaction with the lithosphere of mantle plumes rising from the core-mantle boundary, and that the climate and internal history of Venus were strongly coupled throughout much of its history.

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