Claystone facts for kids
A claystone is a type of mudrock that doesn't break apart easily. Imagine a very fine, hardened mud – that's a claystone! These rocks are made up of tiny particles, mostly clay, that have been pressed together over a long time.
What is a Claystone?
To be called a claystone, at least half (50%) of the rock must be made of clay. The particles in clay are incredibly small. They are less than 1/256th of a millimeter across. To give you an idea, a clay particle is about 1,000 times smaller than a single grain of sand!
Because clay particles are so tiny, they can travel very far in water before settling down. This means claystones usually form in very calm, quiet places, like the bottom of deep lakes or oceans, where fine mud can slowly build up.
What is Clay?
Clay is not just dirt; it's a special type of mineral. There are about 35 different kinds of clay minerals found on Earth. These minerals are what make mud feel sticky or able to be molded, like when you play with clay.
While most clay-sized particles are indeed clay minerals, other materials can also break down into tiny pieces the size of clay. These include quartz, feldspar, iron oxides (like rust), and carbonates.
How Claystone Forms
The way clay forms is quite interesting. It can come from several places:
- Soil: As rocks and minerals in soil break down over time, they can form clay.
- Volcanic ash: When volcanoes erupt, they release fine ash that can turn into clay.
- Glaciation: Huge sheets of ice, called glaciers, grind down rocks into very fine particles, creating clay.
- Old mudrocks: Even ancient mudrocks can weather and break apart, becoming a source for new clay.
Once these tiny clay particles are formed, they are carried by water to quiet areas. Over millions of years, layers of this clay mud build up. The weight of the layers above presses the mud together, squeezing out the water. This process, called compaction and cementation, turns the soft mud into hard claystone.
