Trampoli - (53-57) Lava Ruins entry
Trampoli - (52-57) Mountain Road
Trampoli - (39-42) Mountains road - left side of Kross' farm

The Lava Ruins is available in Rune Factory: Frontier, after you have completed the Green Ruins. Kanno would introduce you to a sprout, on the side of the Mountain's Road, that clear debris and slowly open a way into this new dungeons. A Rune's stone would also be required to grow this tree.