This Magellan radar mosaic shows a portion of the Lada Terra highlands on Venus. The image, centered near 60 degrees south latitude and 15 degrees east longitude, covers an area about 1600 kilometers (970 miles) north-south by about 1,840 kilometers (1,100 miles) east-west. The large circular feature in the north-west of the image is the 500 kilometer (300 mile) diameter Eithinoha corona. Coronae are thought to have formed as hot magma within the Venus crust migrates towards the surface, causing up-bowing of the crust and formation of a ridged boundary surrounding a central region of volcanism. Several lava flows and small shields can be seen in the center of this structure. The bright lines extending away from the corona are cracks and rifts that are probably a direct result of the crustal stresses associated with the formation of the corona. The arch in the lower left of the image is the boundary of another large corona. Extensive volcanism has also occurred in the plains and gives the a patchy or mottled appearance. This plains-forming volcanism has flooded some surrounding higher material, such as the bright patches of tessera east and southeast of Eithinoha corona. Tessera consists of multiple sets of complex intersecting ridges and troughs and often forms large (100's of kilometers wide) continuous patches of elevated terrain. In this case, however, the tessera has been flooded and degraded by volcanic activity, suggesting that the tessera is one of the older features in this region. The narrow channel that can just be seen in the lower central portion of the image was probably formed by the flow of lava from within the tessera out to the surrounding plains to the southwest; lobate lava deposits can be seen at the end of the channel. Two well-preserved, 30-40 kilometer (18-24 mile) diameter impact craters are found in the north central plains and two small circular features in the south central tessera may be degraded impact craters.
