'Hourglass' shaped craters filled with traces of glacier

This unusual structure with traces of a glacier is located in Promethei Terra at the eastern rim of the Hellas Basin, at about latitude 38º South and longitude 104º East. A so-called ‘block’ glacier, flowed from a flank of the massif, past mountains several thousand metres high, into a bowl-shaped impact crater (left), nine kilometres wide, which has been filled nearly to the rim. The block glacier then flowed into a 17 kilometre wide crater, 500 metres below, taking advantage of downward slope.