Nine geologic units are identified in a recently published Arecibe image of the Venus equatorial region [Campbell, et al., 1990>. A detailed examination of the radar scattering properties of these units using data from the imaging mode of the Pioneer Venus Radar Mapper (PVM) shows them to fall into three distinct classes: 1) dark plains, 2) tessera, narrow-spaced parallel lineaments, and 3) bright plains, mottled plains, ovoids, lineament belts, and edifices. Additional units interpreted to be analogous to those mapped from the Arecibo data are identified in the region imaged exclusively by PVM, and are found to have similar scattering properties. An examination of the scattering properties of units mapped as tessera-Tellus Regio and eastern Beta Regio, as compared with the northern flanks of Thetis Regio-leads to the conclusion that part of Thetis possesses characteristics similar to Tellus. ¿ American Geophysical Union 1990 |