Astronomy Mars: ‘Hourglass’ shaped craters filled with traces of glacier

Discussion in 'Astronomy' started by mscbkc070904, Mar 20, 2005.

  1. mscbkc070904

    mscbkc070904 Premium Member

    This unusual ‘hourglass’-shaped structure 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, an ice stream with a large amount of scree (small rocks of assorted sizes), flowed from a flank of the massif 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.

    The Martian surface at mid latitudes and even near the equator was being shaped by glaciers until a few million years ago. Today, water ice could still exist at shallow depths as ‘fossil’ remnants of these glaciers.

    Numerous concentric ridges are visible and appear similar to ‘end moraines’ (hills of scree that form as an extending glacier pushes material ahead and remain after its retreat). Furthermore, there are parallel stripe-like structures that are interpreted as middle moraines, displaying the flow direction of these glaciers.

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