Groundwater

Groundwater

» Some water from the rainfall received on the earth's surface seeps through the ground.
» This water trickles down until it reaches an impervious rock.
» Water accumulated under the ground surface in this manner, is called ground water.
» Some rocks on the earth's surface are porous and some have cracks or joints.
» Water seeps in through these pores or joints.
» Groundwater gushes out in the form of springs.

Land forms created by the actions of groundwater

Sink holes

» Water on the ground surface seeps through limestone. Some portion of the limestone dissolves in that water. If this process takes place continuously, it makes holes in these rocks.
» As this process continues over a number of years, these holes get enlarged. These holes are called sink holes.

Caves

» In limestone region, water goes very deep through sink holes.
» If there is a layer of impervious and hard rock underneath, water flows horizontally on the impervious rock instead of going deeper.
» Hence, soft rocks get eroded and a cave is formed.

Stalactites and stalagmites

» Inside the cave created by groundwater under the ground surface in a limestone region, water is always seeping through the roof. This water contains calcium carbonate.
» As the seeping water evaporates, some of the calcium carbonate, it contains, is deposited on the cave's roof. This deposition continues to grow very slowly. Hence a column is seen growing from the roof towards the floor. It is called a stalactite.
» The water dripping on the floor of the cave also evaporates leaving behind calcium carbonate which accumulates over a period of time.
» A column then starts growing from the floor to the roof. This column which grows upwards is called a stalagmite.
» Stalactites and stalagmites are observed in the Parner Taluka of Ahmadnagar district, in Bastar District in Chhattisgarh and also in the Karst region of former Yugoslavia now Serbia and Montenegro.