Your discovery of 'Numinor' in C.S.L.'s That Hideous Strength is discovery of a plagiarism: well, not that, since he used the word, taken from my legends of the First and Second Ages, in the belief that they would soon appear. They have not, but I suppose now they may. The spelling Numinor is due to his hearing it and not seeing it. Númenóre or Númenor means in High-elven simply West-land. As for the shape of the world of the Third Age, I am afraid that was devised 'dramatically' rather than geologically, or paleontologically. I do sometimes wish that I had made some sort of agreement between the imaginations or theories of the geologists and my map a little more possible. But that would only have made more trouble with human history.
#169 From a letter to Hugh Brogan 11 September 1955