Answer:
The troposphere
Explanation:
It begins at the surface of the earth and extends out.
The answer to your question is DRIED PLANT MATTER ❤️
The name for such a hole is "caldera" which is a word of Spanish origin meaning "a pot" or a "cooking pot" (thing of cauldron!) - and this word is used because it resembles the shape of this hole.
Often the Calderas are filled with water forming lakes and often there is an island in the middle of the water.