This chaotic terrain is located within central Alpha Regio and is called "tessera." Tessera is the Greek word for "tile" and was first used by the Soviets as a morphometric term to describe complicated terrains in Venera 15/16 radar imagery. This area lies between 25.0 and 26.5 degrees south latitude and between 359.9 and 1.4 degrees east longitude. This complicated type of terrain is often found at relatively high elevations up to 3 kilometers (9900 feet) above the surrounding plains. The largest structures are arcuate ridges and troughs that are about 10 kilometers (6.3 miles) wide and less than 70 kilometers (43.8 miles) long. The presence of multiple linear and curvilinear structures at various scales probably indicates that this area has undergone many episodes of deformation. Narrow graben, trending NW-SE, are ubiquitous in this area and cross-cut virtually all the other structures. Thus, these graben appear to represent the latest phase of deformation in the area.
