The lens-like appearance of this feature is probably due to shearing of the surface, where areas have slid past each other and also rotated slightly. Note that in several places in these images, especially around the border of the lens-shaped feature, bright ridges appear to turn into dark grooves. Analysis of the geologic structures in areas like this are helping scientists to understand the complex tectonic history of Ganymede. Two impact craters surrounded by an unusual ejecta blanket dominate this high resolution image of the surface of Jupiter's moon, Ganymede. NASA's Galileo spacecraft imaged this region as it passed Ganymede during its second orbit through the Jovian system.
North is to the top of the picture and the sun illuminates the surface from the southeast.
The craters are situated in a region of bright grooved terrain named Byblus Sulcus, located in the northern part of Marius Regio at 39 degrees latitude and 201 degrees longitude. The distinctive ejecta blanket that surrounds them is darker nearer the craters and brighter further away. The flow was probably icy surface material melted by the energy released during the impact that formed the crater.