In our geology focus we’ve gotten past past types of rocks and into the work of water. BW decided to do his on caves. His mom helped by writing down some of his paper as he dictated it.
Caves are dark, hollow spaces in the ground, in ice or in a mountain. Sometimes they are underwater. They can be found all over the world. A long time ago, people lived in caves; but still, caves are homes to animals like blind fish, bats, foxes, owls, mice and snakes. Back in the ice age cave bears and saber tooth tigers lives in caves.
One type of cave is called the lava tube. It is made when lava flows down the volcano and the outside hardens. The air cools the outside layer of lava. The inside lava flows like water in a pipe until it flows out.
Glacier caves form on mountains with glaciers. The sun melts away a hollow tube of ice. The water flows away. Sometimes the sun doesn’t melt it away. Sometimes the glacier is on top of a hot spring or a volcanic vent.
Limestone caves are the most common caves. They form when water erodes the rock away. When water trickles through rock it is called an aquifer. But that’s only the beginning of the
process! Next, the water erodes the rock and forms underground rivers. The rivers flow faster and faster and that causes more erosion.
In millions of years the river forms underwater caves. Sometimes the water goes out to sea. Sometimes the water table drops because of extreme drought or climate change. The water table is the level of the water. Sometimes you can see the water table as ponds, lakes, or even oceans. Or, it can be underground.
Dry caves form when the water table drops. The caves dry out. Water drips in over thousands of years drop after drop, forming icicles of limestone. These are called stalactites. Stalagmites are made when the water from the stalactites drips onto the floor. Sometimes they can even keep on growing until they form columns. Stalactites and stalagmites can be orange, grey, or even blue.
As you can see, caves are amazing things. Caves are homes to some of the coolests creatures and some of them are blind!