VEO, PIENSO, ME PREGUNTO

SEE, THINK, WONDER

1. LOOKING INSIDE THE EARTH

First, let’s clarify what we’re studying here: the geosphere. To sum up, the geosphere is the solid part of the Earth where living things live.

What’s the point in knowing the inner structure of the Earth?

Well, only by knowing it, we can understand how the relief is created. So, take a look at this video

This animations with will make it clearer for you.

A BRIEF HISTORY OF GEOLOGIC TIME

2. THE SURFACE OF THE EARTH IS MOVING! HOW THE RELIEF IS FORMED

TECTONIC PLATES AND CONTINENTAL DRIFT

Yes, that’s right. The lithosphere (crust and upper mantle) is cracked.

There are several pieces called plates which slowly move due to inner forces of the Earth. The plates collide or separate creating new relief forms and other phenomena. We call this plate tectonics.

Here's how it works

LA DERIVA CONTINENTAL Y LAS CÉLULAS DE CONVECCIÓN DEL MANTO

Want more visual help?

This animation shows the different plates in the world. You can set the options and watch the movements.

THE THREE BASIC MOVEMENTS OF THE PLATES. PLATES BOUNDARIES

You can learn the basics by watching this animation:

Let’s explain everything a bit more

a. COLLISION (convergent boundaries)

The first thing we need to have into account is that some plates are thinner and some are thicker. Ocean plates are thinner than continental plates. Knowing this, the collision can occur in different ways:

- Collision between an oceanic and a continental plate

The ocean plate, thinner, slides under the continental Pate. This process in called subduction. There are lots of earthquakes and volcanic eruptions.

The oceanic plate melts as it re-enters the mantle. The magma rises and erupts. This creates a volcanic mountain range near the coast of the continent. This range is called a continental or volcanic arc.

Did you know that The Andes Mountains are a volcanic arc created by the collision of the Nazca plate and the South American Plate?

- Collision between an oceanic and another oceanic plate

When two oceanic plates collide, one usually slides under the other, and in the process a trench is formed. Also, a lot of volcanoes are erupt.

Over millions of years, the erupted lava and volcanic debris pile up on the ocean floor until a submarine volcano rises above sea level to form an island volcano or even a volcanic arc.

As an example, the Marianas islands and Marianas Trench

Japan

FIND OUT!

Another wonderful example are the Aleutian Islands next to Alaska. Can you find them using Google Earth? Explore the area and locate the trench.

- Collision between a continental and another continental plate.

When two continental plates collide, neither is subducted. Instead, the crust usually folds upwards creating mountain ranges.

The Himalayas is a good example of this case.

b. Separation (divergent boundaries)

We find divergent boundaries where plates are moving apart and new crust is created by magma pushing up from the mantle.

Perhaps the best known of the divergent boundaries is the Mid-Atlantic Ridge. Seafloor spreading over the past 100 to 200 million years has caused the Atlantic Ocean to grow from a tiny inlet of water between the continents of Europe, Africa, and the Americas into the vast ocean that exists today.

Iceland is in its way and it’s cracking in two.