Describe Earth’s Internal Layers– composition and characteristics.

Introduction

Humans have sent spacecraft to every planet in the solar system, including Pluto, which is, at its closest, nearly 3 billion miles away!
In contrast, it’s only about 4000 miles to the center of the earth, and yet we’ve never drilled any deeper than about 8-10 miles down!  And, in fact, the deepest rock samples we have ever laid hands on (from volcanic eruptions) come from only a couple hundred miles down.

It is testimony to the exceptional power of scientific investigation– using all sorts of tools like planetary modeling, meteorite study, heat flow data, gravity data, magnetic data, and primarily seismic wave information– that we really know quite a bit about earth’s internal layering and composition!

Most people recall from elementary or middle school science that Earth’s interior has a layered structure.  Fundamentally, it’s pretty simple– Our planet (like the other “terrestrial worlds,” e.g. mercury, venus, and mars) has a metallic CORE, surrounded by a rocky iron and magnesium rich MANTLE (really making up the bulk of our planet), which is in turn surrounded by a very thin (relatively speaking) CRUST.

More interestingly, we might ask if this layered structure has always been present?
Or, how do scientists actually go about probing the remote interior?
Is it mostly liquid rock down there, as most people think? (In fact, the answer is no, very little in the way of liquid rock deep in earth, as there is too much pressure!)
Or, how does the earth’s deep interior lead to plate tectonics, and therefore mountain building, volcanos, earthquakes, etc.?

Please watch this short video and take a trip through the various layers of the Earth down to its core:

YouTube Earth Interior

Learning Outcomes

• Analyze and compare the properties, material, and layers within the Earth’s geosphere.
• Understand how we know about the Earth’s interior and its magnetism.