Caves are made through the processes of chemical and physical erosion over a long period of time. Water that has absorbed carbon dioxide chemically reacts with limestone bedrock, causing the limestone to erode.Continue Reading
As raindrops fall through the atmosphere, they absorb carbon dioxide. The carbon dioxide helps the rain water to become acidic, which is necessary for it to react with limestone. When the rain lands on the ground, it is absorbed into the soil. As the water continues into the ground, more carbon dioxide is absorbed, helping the ground water to become even more acidic in nature. The water continues to travel through the ground until it runs into rock.
If the rock that the water happens to meet is limestone or dolomite, a cave can form. A chemical reaction occurs between the water and limestone, which opens a larger and larger space within the rock. Over time, the space increases in size and allows more water to flow through. This water, in turn, continues the process of erosion. This physical erosion washes both rock and sand away, making the cave larger and forming a stream underground. This process can take hundreds of thousands or millions of years to complete.Learn more about Earth Science