Metamorphic

So, volcanoes form when plates converge. The subducting plate melts and provides magma for the volcano. 

Main types of volcanoes:

Shield: It’s flat, wide, it’s basically layers of layers of lava piled and dried on top of each other. It’s mafic, so it’s lava has a very low viscosity, which means liquid-ish. 

Here’s one from Hawaii:

Strato volcano/Composite volcano: It’s alternated layers of lava and pyroclastic material (volcano remains). Very explosive and it’s magma is very high viscosity. So, thick, molasses-like lava.

Take a look at Mt. Rainier:

and cinder cones: they’re completely made up of pyroclastic material, rock fragments, so it’s like a perfect cone shape. It can have any type of lava, and it’s only semi explosive.

Speaking of which, why are volcanoes explosive? Because they get all clogged up with magma and that causes pressure to rise. Eventually the pressure gets too high and it just has to blow! 

How? Well, you should know that there are three different types of rocks that we mainly talk about. 

Sedimentary. 

Igneous

Metamorphic.

There are the three kinds of rocks that circle the Rock Cycle. And, if you’ve been paying attention, you would know we’ve already talked quite a bit about sedimentary rocks. So, if you need a review, sedimentary rocks are formed by weathering and erosion. If you need to know the types, go back through the blog. Just turn around. Stop right now.

First, we would have to determine the rock’s age. Did you know there’s two different types of aging? Relative and absolute?

What’s the difference? Well, relative would be like saying, this rock is older than this rock. Or this tree is the oldest relative to those other three trees.

While absolute aging, is saying that rock is 150 millions year old. And that tree is 23 years old. Get the picture?

So, to observe a rock’s history, we would need to determine it’s absolute age first, which can be done somewhat accurately through radiometric dating.

Alright, so here’s a picture of the most common image of how the inside of the Earth looks like. We’ve got the:

Inner core, which is solid, and the hottest part of the Earth.

Outer core, liquid, also very hot

Mantle, now careful here, the mantle also breaks up into two portions: the asthenosphere and the lithosphere

Asthenosphere is plastic-y, fluid-ish. Something along the lines of molasses. Burning, hot molasses.

Lithosphere is solid, and very hard. Also hot. The closest layer to us, to the Earth’s crust, yet we’ve yet to break into it.

Crust, the only part we’re very familiar with, somewhat…

P and S waves! That’s the most concrete evidence we have anyways…