Arecibo radar images of a portion of the equatorial region of Venus provide the first high resolution (1.5-- to 2.0-- km) synoptic coverage of Beta Regio. Within this area, tesseara, a complex deformed terrain, is identified as a major geologic unit with the largest region corresponding to a plateau on the east flank of the highland. Three models are proposed to explain the origin and evolution of Beta Regio and are identified as Mantle Plume/Passive Crust, Mantle Plume/Active Crust, and Mantle Plume/Crustal Spreading. The mantle Plume/Passive Crust model appears to be the most consistent with the geology in this region and suggests that a plume disrupts a preexisting region of tessera. ¿American Geophysical Union 1991