Number 87 (Story #3), July 6, 1992 by Phillip F. Schewe and Ben Stein PLATE TECTONICS ON VENUS? In its recent mappings of Venus, the spacecraft Magellan seemed to rule out any global-scale plate tectonics on the planet, but some scientists re-analyzing its images believe that there may be local tectonic processes at work. At the Spring meeting of the American Geophysical Union in Montreal, Dan P. McKenzie of Cambridge University described his studies of Venusian coronas, quasicircular regions on the planet with volcanic activity below and deep troughs at the edges. He found that the 4600-km Artemis corona, located in a high-altitude equatorial region on the planet, has 4-km deep troughs with features resembling those of the Earth trenches where the sinking of crust takes place. Specifically, the trough surrounding Artemis has chasms whose edges have distinctive bulges resembling the shape that Earth trenches acquire when crust sinks into the Earth. The bulges may represent crust formed from cooled volcano lava sinking into the planet. However, evidence for this process has only been clearly found on Artemis, and this plate-tectonic like process may not occur on the smaller coronas on the planet. (Science, 19 June 1992.)