That the stream of Nen Lalaith came down from Amon Darthir is confirmed by textual references, but the status of Glithui is less clear. It certainly flowed out of Ered Wethrin, and seems to have come from the general region where Amon Darthir stood, but lacking a specific geographical location for the mountain, it is difficult to make the association with certainty. The river Teiglin also emerged from Ered Wethrin in this general region, though its sources seem to have been rather too far to the west to be directly associated with Amon Darthir.

Amon is well established as a word for a hill or isolated peak, but the meaning of Darthir is not immediately obvious. It may be related to the root dar-, 'endure' or 'remain', for which we have a derivative dartha which would imply that Amon Darthir meant 'enduring mountain'. Alternatively, in The Book of Lost Tales (The History of Middle-earth, volume I) we have a term dara, 'lofty', from which derives daroth 'mountain peak'. This would give us a meaning something like 'lofty mountain', which fits well, but given that this term comes from a very early incarnation of the Elvish lexicon, it is difficult to be sure how applicable it may be.

We have no map that marks the exact location of Amon Darthir, but we do know that it stood above the sources of the river Glithui on its southern side. The fact that the Silmarillion map shows a particularly dense region of tall peaks in this area allows us to place Amon Darthir, at least in general terms, with a considerable degree of confidence.