The Magellan data and the analyses of its Science Team and other investigators have answered some of the fundamental questions about the geology and geophysics of Venus. Many other questions, some at least as fundamental, have been raised. The most important of these center around the likelihood of a global resurfacing event at 300--500 Ma, followed shortly thereupon by a rapid decline in rates of magmatism and tectonic deformation:
(1) What plausible mechanisms exist for global resurfacing and the mantle dynamics that accompanied it? Layered convection [ Herrick and Parmentier, 1994], formation and catastrophic recycling of a layer of chemical residuum at the top of the mantle [ Parmentier and Hess, 1992], and oscillatory convection [ Arkani-Hamed et al., 1993] are all possible mechanisms, but require elaboration and/or further testing.
(2) How does the formation of plateau highlands and complex ridged terrain fit into the context of a global resurfacing event? In particular, how could both CRT-forming tectonism and plains-forming volcanism undergo the drastic decline in rates that are apparently required to satisfy impact crater observations? What are the modes of tectonic deformation that lead to CRT and can they be explicitly decoupled from the formation of crustal plateaus?
(3) What rates of magma effusion are required to form canali and
large flow fields on Venus? Could such rates of magmatism be
supported over the 
m.y. of a global resurfacing event?
Are the plains themselves primarily due to large-scale outpourings
or are they primarily formed by the mix of small shields, lava
tubes, and flows that characterize the Snake River Plain on Earth?
Can flood-type volcanic events on Venus form both the plains and
the thickened crust of plateau highlands?
(4) Are the estimates of the thickness of Venus' mechanical lithosphere correct? If so, can they be reconciled with an interior that is still hot enough to convect? Or is Venus geologically ``dead?'' How can such scenarios be reconciled with the extreme topography and apparent lack of relaxation in Maxwell Montes?
(5) Is subduction occurring today on Venus? Are there other explanations for the extreme topography and strong gravity signal observed at some chasmata and coronae?
(6) To what extent does the geology we observe today reflect a
``pre-resurfacing'' Venus? For example, do the presently
observable tectonic features reflect the thermomechanical
condition of Venus' lithosphere at 
Ma?
We can only hope that a combination of increasingly sophisticated physical models and a continuing program of Venus data analysis, particularly analysis of Magellan data, will help to answer such questions. This review has touched on some of the important new findings in Venus geology and geophysics. It is neither complete nor comprehensive; the study of Venus has grown too quickly for that. Rather, it is an attempt to point out areas of research that must be more closely and intensively examined if we are to understand what increasingly appear to be fundamental differences in the tectonic and magmatic evolution between the Earth and her sister planet.
Acknowledgments.This work was supported by the Venus Data Analysis Program, NASA grant NAGW-3484.