This is a Magellan radar mosaic of the Lavinia region of Venus. The mosaic is centered at 45 degrees south latitude and 350 degrees longitude and covers a region 1840 kilometers (1100 miles) east-west and 1600 kilometers (970 miles) north-south. The north-south black bars are regions of missing data. This topographically low region exhibits many diverse geologic features. The dominant structures are the tectonically deformed lineament belts which appear on this image as concentrated regions of sub parallel bright lines. These belts, which are slightly more elevated than the surrounding plains, are interpreted to be composed of a series of ridges formed by the compression of the upper layer of the planet. Individual ridges within a belt are a few kilometers wide and tens of kilometers long. The medium-gray plains surrounding these ridge belts are interpreted to be volcanic in origin. Small (less than 20 kilometer or 12 mile diameter) circular patches in the plains, such as those located in the upper left of the image, are believed to be small volcanic shields. Other signs of volcanism are evident in the bottom center and middle right of the image. These bright and dark lobes of material are volcanic deposits that have flowed downhill from source regions not seen in this image. The bottom flow complex is the northern part of Mylitta Fluctus, a region of vast outpourings of lava over 800 kilometers (480 miles) long. The northern part of this flow can be seen to surround a few ridges, suggesting that the ridge belts formed before the eruption of Mylitta. The placement of the small (10-15 kilometer or 6-8 mile diameter) double impact crater on top of the ridges just to the left of Mylitta also supports the idea that the ridge belts are some of the older features in this region.
