DO ROCKS GROW?

Yes, some rocks grow and caves are one of the few places you can see it happen.  Of course, rocks do not grow like you do and they get bigger over thousands of years.  You could watch all day and not see any growth. 

The rocks that grow in the cave are made by dripping water.  This dripping water started out as rain that fell on the surface.   Imagine that the limestone layers above the cave are a like giant sponge that soaks up water from rain and melting snow.  As the water goes through holes and cracks in the rock it slowly dissolves a mineral out of the limestone called CALCIUM CARBONATE.   If you have ever made lemonade you have seen how water can dissolve sugar. Well over time water can dissolve away rocks and minerals too.  Calcium Carbonate is a very common mineral on earth because it is found in so many things like sea shells, limestone, the growing cave rocks and even your bones and teeth.  Well, this Calcium Carbonate stays in the water until the water drips into the cave.  At that point any place where water drips a tiny amount of Calcium Carbonate comes out of the water and crystallizes into a rock called CALCITE.  As more water drips in the cave, more Calcite is formed and so new rocks start and the older ones keep growing.  These growing cave rocks are often called CAVE DEPOSITES because they are made of layer apon layer of Calcite that the water deposited.

STALACTITES are a Cave Deposite that grow down from the ceilings of caves and STALAGMITES are Deposites that grow up from cave floors.  The two depostites sound so much alike it is easy to confuse them so just remember this, "Stalactites have to hang on 'tite' or they would fall from the roof and Stalagmites 'mite' reach the roof if they keep growing".  If these two cave deposites grow together they will form one formation called a COLUMN.  Another common cave formation is called a DRAPERY.  Draperies are deposites that grown down cave walls and so they look like the draperies you might have in your home.

Many people who visit caves are surprised by all the different colors in the cave deposites.  All of these colors are from IRON and other CHEMICALS FROM THE SOIL.  Water can dissolve these out too and it also mixes them with the white or clear Calcite to create many beautiful colors.