Lime stone

Caves are hollows beneath the surface of the earth. The biggest ones are all found in the rock called limestone. The world’s biggest cave, in `Sarawak’, is so large that you could make 800 tennis courts in it. Yet these caves began simply as cracks or holes in the rock, which over thousands of years, were made bigger by rainwater trickling into them and eating them away.

Rocks

Caves are found in rocks other than limestone. That one is made of lava and is inside a Volcano in Hawaii. Sometimes a cave turns into a gorge. This happens when roof falls into reveal underground caverns and far below the river that carved them. When water drips into the cave columns of calcite, called stalagmites grow upwards.

Lime stone- rock

Lime stone is a very common rock. It is made from the skeleton and shells of tiny sea creatures that died millions of years ago. The rainwater that seeps into he grounds very slightly acidic and begins to eat away the limestone. The rainwater eats through the rock. It widens the cracks into pits, passages and caves. Over thousands of years, the passages and caves may join up to make a huge underground system.

City of joy

Calcutta came to be officially known as Kolkata from January 2001. It lies on the Hugli, a tributary of the river Ganga. Here are some of the interesting facts about this historically important city.

• On the banks of the river Ganga, is a famous temple complex. It has one temple of Goddess Kali and twelve temples of Lord Shiva. Ramakrishna Paramahamsa was the priest of the temple. The name of the temple is Dakshineshwar.
• Mother Teresa set up a center for the dying and the destitute. She was awarded the noble peace Prize in 1979 for her charitable work. The center is known as ``Missionaries of charity’.
• The Indian Museum was established in 1814. It is one of the oldest and biggest museums in Asia. It is commonly known as Jadughar.
• science city Vidyasagar Setu are the important landmark of the city