I'm looking for the name of a short story, probably written between the late 1940s and the 1980s, most likely in a Science Fiction anthology.
The narrator is exploring a polar region, and finds evidence of a pre-human civilization, which destroyed itself with a war that wiped out earthly life. He finds the mummified remains of a guard, non-human (insect-like) at the mouth of a cave/tunnel, looking south. The narrator speculates that radiation killed him at his post, and considers that nuclear war could wipe out the human race in the same manner.
That's all I recall. It is not "The Mountains of Madness" by Lovecraft.