Most reptiles prefer warm, damp surroundings, and transcendent beings like dragonkind are no different. Apart from frost dragons, no one would choose to nest in a cold, lifeless place.
And even frost dragons pick high ground for their lairs almost every single time. It saves them a great deal of trouble and lets them sink what little time they have into infinite sleep.
So the ice field was Adam's best option at this stage. No other dragons to threaten him, no tangle of races to drive off, and those fly-like, thoroughly annoying dragon-slaying heroes would pester him less often out of simple fear of the cold.
That would buy him a great deal of time to develop. As things stood, it was the most ideal nesting site he could have asked for.
"So, Camby, do you know exactly where the ice field is?"
Camby nodded rapidly. "I do, my lord. The ice field lies beside the legendary world boundary — the farthest north of the world we live in."