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| | =Yardangs= | | =Yardangs= |
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| | <div class="post" id="post-1301"> | | <div class="post" id="post-1301"> |
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| | <p>[[File:Video0220_07_08_04_04_51_13.jpg|video0220_07_08_04_04_51_13.jpg]]<br /> | | <p>[[File:Video0220_07_08_04_04_51_13.jpg|video0220_07_08_04_04_51_13.jpg]]<br /> |
| | <em>image by [mailto:jeromegrenier@free.fr Jérôme Grenier], Paris, France</em></p> | | <em>image by [mailto:jeromegrenier@free.fr Jérôme Grenier], Paris, France</em></p> |
| − | <p>On Earth and Mars, persistent, long-term blowing of the wind gradually erodes mountains and hills into elongated streamlined ridges called [http://www.tec.army.mil/research/products/desert_guide/lpisheet/lp235.htm yardangs]. No one has ever considered that the Moon has yardangs - a lack of atmosphere would seem to prohibit their formation - but I can’t look at Jérôme’s image without thinking of them. The [http://the-moon.wikispaces.com/Montes+Haemus Haemus Mountains] here near the crater [http://the-moon.wikispaces.com/Menelaus Menelaus] have been scoured into parallel ranks of rounded ridges. But unlike slowly-formed terretrial yardangs these were carved nearly instantaneously by one stupendous event. And the wind was not atmospheric, but was a hurricane of rock - 10s of meters to flour sized- rushing out over the countryside. These lunar yardangs are the best evidence that ejecta from the formation of Imbrium’s impact basin wasn’t restricted just to ballistic delivery. Some must have screamed (there was enough vaporized material to create a weird atmosphere that could probably carry sound) across the surface as ground-hugging walls of debris, ripping aside anything in its path - notice older crater rims are missing perpendicular to the scour direction. All existing craters were destroyed or strongly modified; the small features visible here, as well as the lavas ponded in the shallow spots, all formed since the passage of the ejecta. And if that isn’t enough to stimulate your observational juices, Jérôme also captured the [http://the-moon.wikispaces.com/Rimae+Menelaus Menelaus Rilles]. These occur in a piece of early mare lavas that has been surrounded by younger ones. And the hill sliced by a short rille doesn’t seem to be a dome, but just a high piece of older lava that escaped burial by the newer. </p> | + | <p>On Earth and Mars, persistent, long-term blowing of the wind gradually erodes mountains and hills into elongated streamlined ridges called [http://www.tec.army.mil/research/products/desert_guide/lpisheet/lp235.htm yardangs]. No one has ever considered that the Moon has yardangs - a lack of atmosphere would seem to prohibit their formation - but I can’t look at Jérôme’s image without thinking of them. The [https://the-moon.us/wiki/Montes_Haemus Haemus Mountains] here near the crater [https://the-moon.us/wiki/Menelaus Menelaus] have been scoured into parallel ranks of rounded ridges. But unlike slowly-formed terretrial yardangs these were carved nearly instantaneously by one stupendous event. And the wind was not atmospheric, but was a hurricane of rock - 10s of meters to flour sized- rushing out over the countryside. These lunar yardangs are the best evidence that ejecta from the formation of Imbrium’s impact basin wasn’t restricted just to ballistic delivery. Some must have screamed (there was enough vaporized material to create a weird atmosphere that could probably carry sound) across the surface as ground-hugging walls of debris, ripping aside anything in its path - notice older crater rims are missing perpendicular to the scour direction. All existing craters were destroyed or strongly modified; the small features visible here, as well as the lavas ponded in the shallow spots, all formed since the passage of the ejecta. And if that isn’t enough to stimulate your observational juices, Jérôme also captured the [https://the-moon.us/wiki/Rimae_Menelaus Menelaus Rilles]. These occur in a piece of early mare lavas that has been surrounded by younger ones. And the hill sliced by a short rille doesn’t seem to be a dome, but just a high piece of older lava that escaped burial by the newer. </p> |
| | <p>[mailto:tychocrater@yahoo.com Chuck Wood]</p> | | <p>[mailto:tychocrater@yahoo.com Chuck Wood]</p> |
| | <p><strong>Technical Details:</strong><br /> | | <p><strong>Technical Details:</strong><br /> |
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| | Rükl charts 23 & 24<br /> | | Rükl charts 23 & 24<br /> |
| | [http://astrosurf.com/grenier/ Jérôme’s website]</p> | | [http://astrosurf.com/grenier/ Jérôme’s website]</p> |
| − | <p align="center"> | + | <p><b>Yesterday's LPOD:</b> [[August 6, 2007|Smooth Stuff]] </p> |
| − | <i>You support [http://www.lpod.org/?page_id=591 LPOD] when buying lunar books (or ANY book) from Amazon!</i></p> | + | <p><b>Tomorrow's LPOD:</b> [[August 8, 2007|An Outpost of History]] </p> |
| | + | <!-- Removed reference to store page 2 --> |
| | </div> | | </div> |
| − | ---- | + | <!-- End of content --> |
| − | ===COMMENTS?===
| + | {{wiki/ArticleFooter}} |
| − | Click on this icon [[image:PostIcon.jpg]] at the upper right to post a comment.
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