A couple of months ago I traveled into the Moroccan Atlas Mountains. Many times I have seen pictures of landmarks like this one of Aït Benhaddou which show apparently unnaturally flat mountain formations stretching across the horizon.

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My guess is that this is a vestige of the ice age or a huge water reservoir. Unfortunately, I could not find any good source on how they were formed. Thus my question is:

How can these formations be explained?

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    $\begingroup$ Will leave answer to someone more familiar with the complex geography history of that area, but from a superficial look of the picture provided, that looks to me like a classic canyon cut into soft stone base which was then lifted into a mesa. $\endgroup$
    – dlb
    Commented Feb 1, 2017 at 18:57
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    $\begingroup$ @dlb, I concur. The mechanisms for the building of this landscape are probably similar to those responsible for the Grand Canyon. $\endgroup$
    – BillDOe
    Commented Feb 2, 2017 at 0:08

1 Answer 1


Once the sediments (mainly silt and sand) have been deposited as layers in an ocean, when the sea level was much higher. Thus, each layer is very homogeneous in its texture, hardness and stability against weathering and erosion. Therefore vertical forces of erosion have a uniform effect on the entire surface and the ridge remains flat when there is no deformation due to tectonic strain. But lateral erosion has different effects on the different hard layers and so you see ribs on the mountains flanks. So it is mainly due to the layer homogenity and due to the absence of tectonic deformation that you see in the background.

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    $\begingroup$ Could you add some references? $\endgroup$
    – L.B.
    Commented Feb 7, 2017 at 15:35
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    $\begingroup$ I would recommend Understanding Earth from J. Grotzinger (2014) for the basics of geology. The cycle of weathering, erosion, deposition, diagenesis and again weathering of clastic sediment rocks is well explained in this textbook, also tectonics and deformation. $\endgroup$ Commented Feb 9, 2017 at 14:19
  • $\begingroup$ How about a reference that this region is indeed a previous ocean basin? Or this your hypothesis given the visual appearance? $\endgroup$ Commented Mar 9, 2017 at 22:17
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    $\begingroup$ How about proving or disproving it by yourself by looking on geological maps? Of course you can consider this sediment structure as aeolian or river sediments or even as magmatic rocks, you’re a free person. Based on 5 years of earth scineces study I visually identified this structure as marine deposits and provided this as explanation. For me it’s clear ad I can live with my hypothesis, but you are free to consider it as an unanswered question due to lack of references and assume the opposite. You can also ask your doctor for references when he tells you that you have a cold. No offense. $\endgroup$ Commented Mar 13, 2017 at 9:20

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