Types of Rocks
There are three types of rocks, sedimentary, igneous, and metamorphic.
Igneous rocks are formed when lava or magma cool. An example would be granite and obsidian. Igneous is part of the Latin word ignis which means fire. There are about 700 types of described igneous rocks.
Metamorphic rocks are sedimentary and igneous rocks that have been changed by heat and pressure. It is originally protolith rock. They can form deep beneath the Earth's surface.
Sedimentary rocks are formed when layers form and pressure is added. You might find sedimentary rocks in a canyon. Some examples include, limestone, sandstone, and mud stone. Unlike the metamorphic and igneous rocks, sedimentary rocks only need pressure and layers to be formed.