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I'm continuing to work on my map, and one thing that's giving me difficulty is figuring out the geology of a region that I wanted to be similar to the Ethiopian highlands and African rift valley. This area is marked dry highlands on the map below. (It's otherwise a little outdated now, but gives a solid idea for this question.)

map

According to wikipedia the highlands are, well, high, because magma pushed up the surface of Earth, forming a mountain range there and in the nearby Arabian peninsula. This appears to be the reason you get legendarily massive plateaus on top of tectonic plates that are separating, and creating the rift valley. (Or that and some more volcanic activity and erosion.)

My question is pretty simple: Is rising magma and separating tectonic plates adequate to create a region like the Ethiopian highlands in the area marked on the map above, or is there an important context I'm ignoring? If so, what should I do to justify it?

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    $\begingroup$ There's a bit more about it to do with wind and weather patterns created by oceanic currents I think. $\endgroup$ – TCAT117 Feb 12 '18 at 23:23
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    $\begingroup$ I wish I knew. I'm no expert (just someone on the internet) but my best guess is that it partially has something to do with two continental plates moving over an oceanic plate to collide. $\endgroup$ – skout Feb 12 '18 at 23:33
  • $\begingroup$ Get rid of those "rising magma" ideas, they're confusing you. I suggest reading up on tectonic plate movement. Of particular interest would be India, which created the Himalaya mountains by being rammed up into what is now Asia. This was caused by plate movement over millions of years. $\endgroup$ – Tim Feb 14 '18 at 0:58
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    $\begingroup$ You don't do those two things simultaneously. You can either push the plates together (create mountain), then pull apart a few millions years later (create rift). Or to create the uplift, start with a supervolcano which only needs a hotspot. Remember that plates change movement over time, so that could be useful. $\endgroup$ – Tim Feb 14 '18 at 1:18
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    $\begingroup$ @Tim The highlands Era is asking for are not the product of converging plates or orogeny. See my answer below. $\endgroup$ – rek Feb 14 '18 at 6:24
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The answer is a simple "yes".

The Ethiopian highlands are the product of flood basalt forming plateaus with repeated or sustained eruptions for thousands (or millions) of years. Similar events created the Deccan Traps in India, the Siberian Traps and Iceland, and others (shown in purple below):

World map showing major geologic provinces

All of these formations are associated with rifts or seafloor spreading, and mantle plumes. Your map indicates the same combination of features, so yes, you have the recipe for a stepped highland as found in Ethiopia.

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