Fun fact: this is the remains of an ancient volcano. The tower that you see here is what is left of a magma chamber or an intrusion of magma into the surrounding sedimentary rocks that solidified, creating hard igneous rock pillars (columnar joints). The rest of the volcano then weathered and eroded over a very long period of time leaving only the hardest rocks.
this post was submitted on 01 Aug 2023
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Interesting! Is this the only one in Wyoming or are there other geological features like this with a similar origin?
I'm glad you asked! Devil's tower is "one of a kind" because the formation of such features are rare. It consists of phonolite porphyry which is an intrusive igneous rock (meaning it formed from cooling magma inside the Earth). Most of the time when you see columnar jointing it is associated with basaltic igneous rocks which are much darker because they contain higher levels of Fe and Mg (mafic) compared to the more silica rich intermediate igneous rocks like the one in question. There are similar geological features, though, including some in Iceland and Scotland (see giants causeway) and as for the hexagonal shape it turns out nature just likes to naturally form them because its easy.
I guess to summarize, there are not many similar formations to compare Devil's tower to, but those that do exist were formed from different magma (more mafic) and did not erode as gracefully as this formation.
That was fun to learn. Thanks for sharing your knowledge with us!
Close encounters of the third kind
Also, "Mato Tipila"