An alternative Venus Warren B. Hamilton*1 Department of Geophysics, Colorado School of Mines, Golden, Colorado, 80401, USA ABSTRACT Conventional interpretations assign Venus a volcanotectonic surface, younger than 1 Ga, pocked only by 1000 small impact craters. These craters, however, are superimposed on a landscape widely saturated by thousands of older, and variably modified, small to giant circular structures, which typically are rimmed depressions with the morphology expected for impact origins. Conventional analyses assign to a fraction of the most-distinct old structures origins by plumes, diapirs, and other endogenic processes, and ignore the rest. The old structures have no analogues, in consensus endogenic terms, on Earth or elsewhere in the solar system, and are here argued to be instead of impact origin. The 1000 undisputed young “pristine” craters (more than half of which in fact are substantially modified) share with many of the old structures impact-diagnostic circular rims that enclose basins and that are surrounded by radial aprons of debris-flow ejecta, but conventional analyses explain the impact-compatible morphology of the old structures as coincidental products of endogenic uplifts complicated by magmatism. A continuum of increasing degradation, burial, and superposition connects the younger and truly pristine of the young impact structures with the most-modified of the ancient structures. Younger craters of the ancient family are superimposed on older in impact-definitive cookie-cutter *E-mail:
[email protected] (version of 20 Nov, 2006) 1 bites, not deflected as required by endogenic conjectures. Four of the best-preserved of the pre-“pristine” circular structures are huge, with rimcrests 800-2000 km in diameter, and if indeed of impact origin must, by analogy with lunar dating, have formed no later than ~3.85 Ga.