The under ground passage in a ringfort is called a souterain. These may have been used to store food or to hide during raids. There is one nearby which links up two areas.
"geothermal"
This would be called a cave.
This oil is called crude oil.
the water that lays under the ground is called ground water.
under ground
A basement is a large room under the ground. A dungeon is a room under the ground.
"geothermal"
yes there is its called the mantle its under the crust
A tunnel
water
Spuds
This would be called a cave.
The underground railroad.
Potato
Aquifers.
This oil is called crude oil.
Sedimentary.