How can water erosion by groundwater form a cave?

1 Answer
Dec 24, 2016

Softer or more soluble rock compounds trapped between harder layers will be dissolved or eroded and carried off by the groundwater, leaving a space that we call a cave.

Explanation:

First, you must understand how the “ground” was formed. It is not a homogeneous mass, but a wildly varying mix of different rock and soil types and layers. They may have been deposited as siltation in a large body of water, or thrown up as magma from a volcano, and then pushed back deeper into the earth by plate tectonics or additional volcanic or deposition activity. Thus, there are different types of rock both intermingled and in strata (layers).

When groundwater seeps into the ground, it finds channels in the pores of the rock. Eventually, the ability of the water to dissolve some types of rock compounds more than others will lead to larger channels, and even underground rivers.

An underground river may cause direct erosion of harder rock as well as the continued dissolution of soluble rock components. When a large amount of soluble material is removed, and the water settles into deeper or different channels, the remaining underground space may be a single cave or a connected series of caves.