Suppose you are a geologist traveling in a region that has limestone bedrock and plenty of rainfall. What features would you expect to find in this landscape? How did they form?

You would expect to find several cave formations. Cave formation begins when acidic rain falls. This acidic rain goes is absorbed by the soil and soon enough reaches the bedrock. If this bedrock is limestone, a cave can form. The acid rain erodes the limestone and after thousands and thousands of years a cave forms as this process is repeated over and over.