The sediment comes from eroded rocks carried there by rivers or ice ... Slate is dark grey/green in colour and can be split into thin layers for use as roofing material. Marble is white or ...

Sure enough, they found the jumbled deposits near the top of some hills contain rocks that have been eroded from much deeper layers and somehow carried up to the top of the hill. “You can tell ...

To the south are ancient highlands, while to the north are eroded, mostly low-lying ... Immediately below the clay layers are older layers of rock that contain no clay; above the clay layers ...

Their erosion over hundreds of kilometers shows ... into the ancient geography and hydrology of Mars.” The clay-rich rock layers within the mounds suggest that an abundance of water was present ...

floats on the mantle layer, which is made of hot, semi-liquid rock. In this case, the merger of the rivers caused erosion to happen more quickly. This process has carried off huge amounts of rock ...

Thousands of hills and mounds on Mars have been found to contain layers of clay minerals ... and mesas in desert areas, where rock formations have been eroded by the wind for millions of years.