Most underground caves are formed by the action of water on rocks:,

There are many different caves formed by nature. Often these caves are found in areas where volcanic activity is widespread, This is because it is formed by molten material, which is known as lava. Mostly with tunnels, There are ice caves. Caves on the enchanting oceans and seas, The underground rocks formed by the action of water on the rocks.

Now we will give you the solution to the question:

Most underground caves are formed by the action of water on rocks: oily sandstone calcareous granitic,

the answer :

limestone,