A cavern is a specific type of cave, naturally formed in soluble rock with the ability to grow speleothems. Caves Caves can be classified into two main categories known as primary and secondary. This classification is based on their origin. Primary caves are developed as the host rock is solidifying. Secondary caves are carved out of the host rock after it has been deposited or consolidated.
Most caves fall in the secondary category.
However, some primary caves may later be enlarged by the forces associated with secondary cave development.