Geological history hidden in the volcanic plains
The evolution of the region could have started with the load caused by the formation of the Tharsis volcanoes which caused stress, resulting in numerous fractures. Then, the region was repeatedly covered by basaltic lava flows. Wrinkle ridges formed as result of regional compression. In a later stage, the region was covered by volcanic ash and dust. Finally, the valleys were carved into the surface. It is unclear, where the waters came from. Some of the valleys appear to be incised deeper into the rock, others are more surficial and broader. They also appear to have their source at different height levels, which could be a hint to groundwater sapping. However, the intense erosion makes it difficult to assess the provenance of the waters. The height differences within this image are breathtaking 4500m! Since the formation of Protva Valles about 3.8 billion years ago, the geology has remained largely unchanged.