Fossils on Friday – Igneous Rock

Welcome back to Fossils on Friday, as we continue our exploration into geological principles and terminology. Last week, after we looked into sedimentary rock, I promised a very explosive rock…

That explosive rock is called igneous rock. Igneous rock is brand new – meaning it is made out of molten lava or melted rock. To understand a bit more, we need to chop the Earth in half…

See the source image

Here is a cross section of the earth, which is made up of many layers, each one behaving differently. The crust is solid and relatively thin, being only a few miles thick. Beneath that you have the mantle, which contains a molten layer of magma. The mantle is where the igneous rock originates from.

The crust is not a solid, continuous part, like the peel on an orange. It is made up of several parts called plates. These plates can crash into each other, and sometimes even shove themselves down under another plate. These lines, where the plates come together, are often a weak spot, which means that the magma can push itself up through the cracks, spilling out onto the crust. We call this a volcano.

Thus magma is the start of the igneous rock journey. But there are several different types of igneous rock, as well as several different ways that a volcano can behave – so we will continue our exploration next week!