Thread:Gen. Grievous1138/@comment-26236093-20150626233138/@comment-27723099-20150627115804

This sounds as if Nogrod was in the middle between the northern and southern Blue Mountains, the part that was destroyed when the mountains broke in two parts. This is also supported by another article:

"At the location of Mount Dolmed and the Dwarven citadel of Nogrod, Belegaer broke through the mountains, creating the Gulf of Lune."

- http://lotr.wikia.com/wiki/Gulf_of_Lune