True colour plan view of Pyrrhae Regio
True colour plan view of Pyrrhae Regio
Pyrrhae Regio, south-east of Eos Chasma, a side valley of the Valles Marineris, is a typical three-to-four-billion-year-old highland plateau with numerous craters, some of which are already heavily eroded. In its northern part (right, in the image) an unusual landscape is noticeable. This is an area about 50 by 40 kilometres, consisting of interconnected depressions, terraced slopes on the sides, and in the far north seemingly ‘chaotic’ hills in a dense arrangement. A long time ago, this ‘chaotic terrain’, a term used by geologists researching Mars, was formed here after ice thawed under the surface of the highland plateau, flowed away and the resulting cavities collapsed. Just visible are heavily eroded valleys that flow into the depressions from the south, an indication that there has also been an outflow of water on the surface. The three old craters in the south, which are between 20 and 50 kilometres in diameter, are filled with sediment.
