Draconis tales chapter 39

Amethyst flew over the last of the ember ring until he reached the edge of a huge cliff plummeting into a circular valley with a huge mountain in the exact centre, he flew down into the valley, with Obsidian flying nearby and Bluefeathers, Lupus and the wolf, which had stopped glowing now except inside it's eyes and mouth, climbing down the cliff.

Inside the valley, Amethyst noticed it was much colder than the ember ring, cool enough for normal trees to grow.

Flying across the plain towards the mountain, he looked for good ways in. Over the top would be too obvious, but from what he had learned from the heir, he knew that there was a secret network of tunnels inside the mountain leading into the open crater of an extinct volcano, which would seem a likely place for the crystal wyvern queen to have her home.