Astronomy:Concentric crater fill
A concentric crater fill is a landform where the floor of a crater is mostly covered with many parallel ridges. It is common in the mid-latitudes of Mars, and is widely believed to be caused by glacial movement. Areas on Mars called Deuteronilus Mensae and Protonilus Mensae contain many examples of concentric crater fill.
Concentric crater fill, like lobate debris aprons and lineated valley fill, is believed to be ice-rich. Sometimes boulders are found on concentric crater fill; it is believed they fell off the crater wall, then were transported away from the wall with the movement of the glacier. Erratics on Earth were carried by similar means.
High resolution pictures taken with HiRISE reveal that some of the surfaces of concentric crater fill are covered with strange patterns called closed-cell and open-cell brain terrain. The terrain resembles a human brain. It is believed to be caused by cracks in the surface accumulating dust and other debris, together with ice sublimating from some of the surfaces. The cracks are the result stress from gravity and seasonal heating and cooling.
Close-up view of concentric crater fill, as seen by HiRISE under HiWish program Note: this is an enlargement of previous image of a concentric crater. Location is Phaethontis quadrangle.
Wide-view of concentric crater fill, as seen by HiRISE. Location is the Casius quadrangle.
Well-developed hollows, as seen by HiRISE under the HiWish program. Location is the Casius quadrangle. Note: this is an enlargement of the previous image that was taken by CTX.
This series of drawings illustrates why researchers believe many craters are full of ice-rich material. The depth of craters can be predicted based upon the observed diameter. Many craters are almost full, instead of having bowl shape; hence it is believed that they have gained much material since they were formed by impact. Much of the extra material is believed to be ice that fell from the sky as snow or ice-coated dust.
Wide view of concentric crater fill, as seen by CTX Location is the Phaethontis quadrangle.
- Casius quadrangle
- Climate of Mars
- Deuteronilus Mensae
- Fretted terrain
- Impact crater
- Glaciers on Mars
- Protonilus Mensae
- Water on Mars
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Original source: https://en.wikipedia.org/wiki/ Concentric crater fill. Read more