ESA Science & Technology - '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 38° South and longitude 104° 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, nine kilometres wide, which has been filled nearly to the rim (right). The block glacier then flowed into a 17 kilometre wide crater (left), 500 metres below, taking advantage of downward slope.

 
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