We are all familiar with rivers which flow on the surface of the earth. But strangely enough there are some underground rivers too. Do you know how under ground rivers are formed?
There are many reasons which give birth to underground rivers.
An underground river is formed when the uppermost surface of the earth easily allows rainwater to pass through to a more solid soil-structure. This water starts flowing due to the pressure of the upper water and takes the shape of an under ground river.
The flow of water within rocks depends upon two properties: the rock’s porosity and permeability. Porosity is that fraction of a rock’s bulk volume which is made of void. In general, elastic rocks are porous. Crystalline rocks have low porosity. Permeability is a rather general term used to describe the case with which a fluid can flow through the void of a rock. It mainly depends upon the size of the void. Underground water flows along a path following the steepest slope.
Limestone rocks are honeycombed with tunnels and cones. When the rainwater which contains certain amount of acid falls on them an interesting process takes place. The water starts flowing through their tunnels and caves seeking a way out. As the water moves along it wears away more and more of the surrounding rock to produce long tunnels which eventually turn into under ground rivers. These rivers finally reach the sea by surfacing at certain places.
These are another process through which an underground river is created. When a powerful spring can’t sprout forth, owing to the solidity and compactness of the rocks, it starts flowing underground.
The distance travelled underground by such a river varies. In some cases it is more and in some others less. The famous Rhine of France travels only a short distance underground. There is a famous underground river in Somerset (U.K) speleogists have tried to follow the course of some underground rivers but many passage are too narrow to get through. In this regard a process has been devised by some researchers. It involves mixing of certain dye in river’s water to recognize it when it surfaces again.
Underground rivers creates many Deep caves and that places home to many unknown creatures, most of the caves are created by the Rain water flow, rivers. Some Rivers are joins directly to the oceans and Some of the Rivers in the middle of the land then joins to Ocean.