The Pacific sector of Antarctica consists of tectonic terranes amalgamated along the convergent margin of Gondwana, intruded by arc plutons, and affected by transcurrent plate interactions in Cretaceous (Marie Byrd Land, Antarctic Peninsula) and Tertiary (north Victoria Land) time. The region has distinctive geophysical characteristics, including freeboard position of its thinned continental crust since Cretaceous time, thermal structure, and the inverted gravity signature of Ross Sea basins. Its subsidence and sedimentation history is unusual in light of the two-stage Cretaceous extension recorded in the Ross Sea and Marie Byrd Land. Inherited crustal structures and thermal perturbations influence the Miocene to present volcanism that coincided with growth of the Antarctic ice sheet, and they affect ice flow patterns today. This paper explores these factors in order to gain perspective on evolution of the West Antarctic rift system and to discover linkages between the discrete geological entities of West and East Antarctica.