Online Class: Geography 101

This course covers the way humans create order by drawing maps and creating areas that we can recognize. You'll learn how mapmakers divided the oceans and why. The lessons will touch on how culture and experience influence the way people map the world. 

Course Motivation

What is the difference between these two different aspects of geography?

Imagine that people don't exist, or rather that we exist, but had never invented language, books, maps, nations, or any other way of looking at the world that differs from any animal. If that were so, we would see the world composed of water, land, and places that could be recognized mainly by their shapes. If we lived long enough, we might see that the shapes of things changed over time. We might understand that wind and water and the movement of the earth itself cause changes to the landscape. This way of looking at the world is the study of physical geography.

However, we are people, and over time, we have divided the world into human boundaries. We have created nations, states, cities, and towns. Some borders are marked by natural boundaries, such as the U.S. state lines that follow the Mississippi River. Others are created by people and ignore the natural features of the land. The study of countries, and other human based divisions of the planet, is also a part of geography.

In this course, we are going to pay the most attention to natural aspects, covering different geographical forms, such as mountains and rivers, and how they influence changes in the landscape.

To begin, let's look at the way the planet itself was formed. Our most current theories say that about 4.6 billion years ago, the sun began to form out of a huge cloud of dust and gas. Most of this matter went into making the sun, but some of it began to collide and stick together, forming planets, moons, and asteroids. Eventually, these bodies settled into their present orbits. Scientists calculate that this happened fairly quickly, compared to how long the planets have existed, within a period of about 100 million years.

Scientists theorize that at some time during this process, a large meteor about the size of the planet Mars collided with the Earth. The impact of this collision tore away some matter from the Earth. This matter eventually became our Moon. Scientists date this event to about 4.5 billion years ago because astronauts have found rocks on the moon that are 4.47 billion years old.

This was a time when many meteors and asteroids collided with the Earth, other planets, and each other. Although this period only lasted about 600 million years, occasional collisions still occur. Every year, tiny pieces of meteors hit the Earth. They do little damage, because they are very small, but every few million years, one may be large enough to affect the planet in a dramatic way. Many scientists believe that such a collision occurred about 65 million years ago, resulting in climate changes that led to the extinction of the dinosaurs.

The remaining Earth matter, very hot from the energy released by colliding dust particles, formed into what we know as Earth. The heaviest and most dense part of the Earth is a solid core in the center of the planet. This core is composed mostly of iron and nickel. That core is surrounded by a molten, or liquid, layer of iron and nickel. Molten rock is also known as magma. A thick mantle of partially cooled rock surrounds that magma. This mantle is rather spongy and filled with pockets of gas. 

The outermost layer of rock, called 'crust' is almost completely cool. The crust contains everything we can see on the planet. The highest mountains and the deepest valleys are all part of the crust. Although we can't see it, the bottom of the ocean is also part of the crust. The only time we catch the smallest glimpse of anything below the crust is when volcanic eruptions push molten rock or gases to the surface of the planet.

The oldest rock found on the Earth to date is about 4.4 billion years old. Because of this find, scientists believe that the Earth managed to cool down fairly quickly after the collision that also created the moon. Scientists estimate that roughly 4.6 billion years ago, the Earth and all the inner planets were formed.

The hydrosphere is what we call the oceans, rivers, lakes, and glaciers that cover most of the planet. The word comes from hydro, meaning water, and sphere, meaning round. The atmosphere is the layer of air (mostly nitrogen, 80%; and also oxygen, 20%) that surrounds the planet. Both the air and water on Earth work to affect the shape of the crust. 

In addition, the crust itself is continually changing. According to the Plate Tectonic Theory, the crust is cracked, like an egg that's fallen onto the floor. Like an eggshell, the pieces more or less fit together. Unlike an eggshell, however, the pieces are always moving, rubbing together, and sometimes overlapping at the edges.

So, we have three large forces that work to change the geography of the world: air, water, and the movement of global plates. These different forces also affect each other. Plate movement can cause volcanic activity, which may affect the movement of wind, and the courses of rivers. 

On top of that, there is the effect of plants and animals on the landscape, and the impact of external forces, such as the gravitational pull of the moon and the occasional collision with meteors. All in all, there are a lot of things that can change the world around us!