There is no such thing as an "underground mountain range" in the traditional sense. Mountains are formed by geological processes that uplift land above the surface.

However, there are geological formations that could be considered analogous to an underground mountain range:

* Submerged mountain ranges: These are mountain ranges that exist beneath the ocean surface. For example, the Mid-Atlantic Ridge is a massive underwater mountain range formed by tectonic plate activity.

* Subsurface geological structures: These can include large folds, faults, and other geological structures that create significant rises and dips in the rock layers beneath the surface. These structures might be considered "underground mountains" in a metaphorical sense.

So, there's no specific name for an underground mountain range, but there are geological formations that could be interpreted as such.