| Risultati della ricerca nelle immagini - "gullies" |
PSP_003252_1425_RED_browse-01.jpgBright Gully Deposit in Terra Sirenum (the "crater" - close-up; false colors)56 visiteAs seen in the context image and here, the appearance of the crater wall differs between the Northern and Southern Sides. On the Northern Pole-Facing Side Walls, prominent gullies with channels and aprons are apparent, with many of these having valley-like alcoves near their tops. The morphology of the gullies is consistent with formation by a fluid, most likely water.
On the pole-facing slopes, ground ice or aquifers may be more stable, being subjected to less heating from sunlight compared to equator-facing slopes.
In contrast, the Southern, Equator-Facing Walls are dominated by rocky debris flows that lack prominent channels.MareKromium
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PSP_007151_1445_RED_abrowse-00.jpgColorful Layers in the Walls of an Unnamed Southern Crater (context frame - MULTISPECTRUM; credits: Lunexit)55 visiteThis image shows an unnamed, bowl-shaped impact crater located in the Southern Highlands. The crater is approximately 4 Km (about 2,5 miles) in diameter and 600 meters (approx. 2000 feet) deep.MareKromium
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PSP_007151_1445_RED_abrowse-01.jpgColorful Layers in the Walls of an Unnamed Southern Crater (extra-detail mgnf - MULTISPECTRUM; credits: Lunexit)55 visiteThis extra-detail mgnf (enhanced to exaggerate color contrast) shows part of the North-facing walls of the crater, deeply carved by landslides. Rocky layers, mostly purplish in color, can be followed for hundreds of meters, poking through the loose materials that cover the slopes.
Locally, the rocky layers show patches of diverse colors (blue, green, yellow). These colors may be indicative of compositional differences in the rocky layers.MareKromium
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Psp_001691_1320_red.jpgGullied Trough in Noachis Terra(False Colors)53 visitePSP_001691_1320 shows gullies in a semi-circular trough in Noachis Terra. The gullies are observed to face all directions.
It is interesting to note that the gully morphology seen here depends on the orientation of the gullies. The morphology differences are most pronounced on the sunlit slope, with the gullies facing South (Dx) being more deeply incised than those facing the West. It is unknown what caused the different gully morphologies, but there are several possibilities.
Gullies are proposed to form at locations determined by the availability of a forming liquid (thought to be water) and/or the amount of insolation the slope receives, among other factors. It is possible that the deeper gullies experienced more erosional events or that their erosional events were more effective for undetermined reasons. It is also possible that the gullies formed at different times such that they did not have the same amount of water — either for an individual flow or total — available to them.
Also, the underlying topography could make the gullies appear relatively more incised without this actually being the case.
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Psp_001691_1320_red~0.jpgGullied Trough in Noachis Terra (extra-detail mgnf - false colors)53 visiteThe majority of the gullies on both sides of the trough appear to originate at a boulder-rich layer seen in this subimage.
The layer appears dark on the sunlit slope because the boulders sticking out from the slopes cast shadows. If these gullies formed by water from the subsurface, then it is possible that this layer is a permeable layer that conducted water to the surface.
The layer is deteriorating and traveling down slope in the form of boulders.
These boulders can clearly be seen in the alcoves of the gullies on both sides of the trough.
Note that the alternating stripes on the lower right (Dx) side of the image are an artifact from camera noise. They are not real features.
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