1º British: The Earth’s relief

After the introduction to Geography and a brief revision of the Solar System, now it is time to start Topic 4. Wait a moment... and what happens with topic 3? Well, one of the “casualties” of this lockdown situation is the precisely the learning of mapping skills (topic 3 and monthly work 5). My experience has taugh me that is quite difficult and students really need the teacher’s support to have clear explanations (a video is never enough for this specifical case) and the possibility of total individual attention to clarify doubts. Therefore, we are skipping this part. Don’t worry, we will study it next year...

But now, as I said, let’s start with TOPIC 4: the Earth’s relief!. Quite interesting one, actually.

By the reading of my theoretical notes, you can see that the Earth, which is a geoid (that is, not a perfect sphere), has a complex structure with different layers:

• The atmosphere is the gaseous layer that covers the Earth. It is not a simple layer, actually: it can be divided in different parts, each one with a different name.
• The crust or litosphere is the outer layer of the Earth: where we live.
• The mantle is the middle layer (but technically divided into two: outter mantle and inner mantle)
• The core is the most internal, deeper layer (also divided into two)

Quite complicate, isn’t it? Look at the following drawing to understand it:

From all this layers, the crust or litosphere is one of the most interesting and active one because it is NOT form by a sigle piece but on the contrary, there are different plate tectonics (such as giant pieces of a puzzle) floating over the semi-solid magma from the mantle. Look:

As you can imagine, being over magma is dangerous. These plates are not static, they move veeeeeery slowly: maybe only 1 or 2 milimetres per year. That movement has important consecuences for us:

• When two of these plates move towards each other (when they collides like a car crash) or when two of these plates move apart from each other, the magma rises throught the gap: a volcanic eruption! (This is so important that we will study volcanoes more in detail next week). This very short video from BBC can help you to understand that movement (1 minute only, in English)

• Some other plates move horizontally, creating friction between them and producing earthquakes!

The Earth is million years old! And that movement of the plates tectonics has been happening since the beginning so, despite 1-2 milimetres looks a very small movement, the continous movement during all those millions of years has changed the look of the Earth a lot. In fact, at the beginning there was ONE single continent, called Pangea (or Pangaea) and over time it broke into pieces that were little by little separated, creating the current continents. That is called the continental drift. Watch this video about Pangea (2’23 minutes, in English).

We can say that the internal forces of Planet Earth are volcanic eruptions and earthquakes. They “create” the relief (a volcanic eruption can make a new mountain to appear… or a full island to dissapear!). Meanwhile the external forces (for example, the wind, the rivers…) “change” the relief by the erosion. Even we, humans, change the relief when we build roads or cities. Look at the following image to see how many different elements of relief we have:

Now, to check that you have really read my notes and watched the videos, send me an email (blogeducativo08@gmail.com) with the answers to the following questions (Last day: Monday, 20 April):

1. What is a hazard?
2. What is a plate boundary?
3. What is continental drift?
4. Who was Alfred Wegener?
5. What type of evidences did he find?
6. Finally, choose TWO words from the drawing “elements of relief” and write a  definition.

That's enough for this week. If you have any doubt or problem, just ask me, ok?