Hi Greg,
This is a very interesting structural complex, and one I've taken some time to study. My image enhancement is below, but let me first say that I have serious doubts that a natural watercourse is the genesis of this artifact. That said, I can't now suggest an alternative hypothesis, except to observe that I find it anomalous.
I do have a few observations, but first my image. I should note that my processing included oversampling and maximum entropy deconvolution. This enhancement includes the full width of the original image, which means it depicts terrain of 2.86 km width, but it is here presented at an enlargement of 50% over the original.
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The feature you point out appears to me to consist of a more-or-less continuous, sinuous lineation composed of numerous, diverse structural elements. However, in few if any locations does it look to me that they could be the result of ordinary water flows. There are many strange features here, so I'll comment specifically on just two, with a few additional observations.
At the upper left of the image, the sinuous trace begins with a strange series of level stages, in which the "sand dunes" have more the appearance of retaining walls. Each in turn appears to retain the topographic level of the elevation above. I do not get the impression that this is a natural land formation, but rather that it is purpose-built, with the intent of creating a series of topographic 'levels' for whatever purpose.
To the right and below the first-mentioned structural complex, there are several examples where the sinuous lineation appears to dip below the surrounding topography, but in virtually each such case, its presence remains detectible through one or another variation of the land surface. Many of the intervening structures appear to have little or no relationship to an originally-existing watercourse -- except, of course, that there is continuity of structural alignment. Otherwise, the purpose of that alignment bears scant similarity to a naturally ocurring river bed.
Near the lower right of the image is a strange situation where, based upon the solar illumination and the shadowing, it seems fairly clear that the lineation procedes a distance UPHILL, near the crest of which it can be seen to cross OVER a "sand dune", which in the immediate vicinity is depressed below the elevation of the lineation. This, within a short distance, is repeated but with the trace of the "sand dune" remaining clearly visible beneath.
Altogether, I find it exceedingly difficult to believe, if this ever was indeed a natural watercourse, that its current appearance could be derived from that original formation. There seems to me much more at work here in terms of formative factors than that.
Wil
