Book 1, Question 64 · Video
Why Do Caves Form? Rain, Rock and Slow Drips!
Caves are nature's underground architecture. Rain picks up carbon dioxide and becomes a weak carbonic acid, which seeps into the ground and slowly dissolves limestone along cracks
Read the full answer →What Crafty Clover says in this video
Intro
Hi! I'm Crafty Clover! Let's discover something amazing. Why do caves form?
The Big Idea
Deep underground, there are hidden rooms, tunnels, and giant halls. They're caves! Here's the big idea: over a very long time, water slowly carves caves out of rock. It's nature's amazing underground architecture!
Weak Acid
Step one: rain becomes a weak acid. As rain falls through the air, and soaks through soil, it picks up a gas called carbon dioxide. That makes a weak acid, called carbonic acid. It's like a little soda fizz!
Limestone Dissolves
Step two: limestone dissolves along cracks. The weak acid seeps into the ground, and slowly dissolves limestone, a rock made of calcium carbonate. Over thousands of years, the tiny cracks grow into channels, passages, and huge caves!
Drips Build
Step three: drips build stalactites and stalagmites. Water full of minerals drips from the cave ceiling. When the water evaporates, a mineral called calcite is left behind, building stone icicles, drop by drop!
A Closer Look
Let's take a closer look inside a cave! Stalactites hang down from the ceiling. They hold tight to the ceiling! Stalagmites grow up from the ground. They might reach the top one day! And drip water collects in little pools on the cave floor.
Quick Facts
Quick facts! A stalactite can take hundreds of years to grow just two and a half centimeters, about one inch! When a stalactite and a stalagmite meet, they make a column. Most big caves take hundreds of thousands of years to form. Curious minds dig deeper!
Think Like a Scientist
Now, think like a scientist! Here's a trick to remember which is which. Stalactites have a C, for ceiling. They hold tight, and hang down. Stalagmites have a G, for ground. They grow up! Now draw a cave, and label both! Be curious, and keep exploring!
Outro
Caves form when weak acid in water slowly dissolves rock, and drips build amazing stone shapes! Keep asking, keep exploring! Crafty Clover can be found on Amazon Books, Google Bookstore, and Apple Books. Available for purchase or download! Bye for now!