5.2 Lithosphere

The word lithosphere comes from the greek word “lithos” which means rock basically saying that the lithosphere is a sphere of rock but this sphere is not the same everywhere. volcanoes, earthquakes and other events shape it.

Definition of the lithosphere: the lithosphere is earth’s layer of solid rock. it is composed of earth’s crust and the upper part of the mantle. the lithosphere includes all elements of relief: mountains, plains, plateaus, volcanoes, etc.

earthquakes happen in the lithosphere also rocks, mountains and volcanoes are formed here. the continental crust is thicker than the oceanic crust. the thickness of the lithosphere changes from place to place it is normally around 70 to 150 kilometers thick.

humans have a constant relationship with the lithosphere. humans take minerals, like copper, and materials, like sand from the lithosphere.

a lot of living organisms including plants live in the lithosphere. they draw the water from the soil and then humans harvest the plants to feed themselves and their animals to make clothing. this is one way how the humans interact with the lithosphere.

Humans are also transforming the lithosphere by burying waste into the ground.

Humans also live on the ground, they build roads and houses there. to do that they use materials from the ground such as stone, sand and oil.

What is relief?

from the relief in your area you can probably tell that the lithosphere is not even.

Definition of relief: Plateaus and shields. Plateaus are vast stretches of flat land that are located at least 300 meters above the surrounding areas. shields form a very ancient relief which have the appearance of slightly rounded plateaus. for example the Canadian shield.

Plains and hills: plains generally have low and flat relief. they sometimes come from ancient seabeds or riverbeds where sand and gravel once accumulated. the Saint Lawrence Plain is an example of a plain. hills are low bulges in the relief.they can be found on plains. Mont Saint-Hilaire is an example of a hill.

Mountains and valleys: Mountains are a very high type of relief, characterized by steep slopes. they are formed when earth’s crust folds and juts out after two tectonic plates collide. when many mountains are grouped up together over a long distance and occupy a large area they are called a mountain range. Valleys are long, low stretches of land. they are generally situated between two mountains and etched out by a body of water. Valleys are caused by erosion from water running off the mountains.

Québec’s relief

the canadian shield is a huge region that occupies the north-east of canada and covers 90% of québec. it is a very old mountain range that has been flattened by erosion. it is between 1 to 4 billion years old. the canadian shield is slightly more elevated comparex to the surrounding areas since it is a plateau.

A large part of north america is covered by the appalachians. in québec these mountains cover the following regions: Estrie, Centre-Du-Québec, Chaudières Appalaches, Bas-Saint-Laurent and Gaspésie. the appalachians are very old. therefore they are lower and flatter than newer mountain ranges such as the rockies in british colombia.

the saint lawrence plain extends along both sides of the saint lawrence river, from the south west of Montreal to the city of québec. this plain comes from the drying of the champlain sea. before it started drying out it covered almost the entire plain, from the canadian shield to the foot of the appalachians. the plain has a few hills called the “montérégiennes” like mont saint hilaire.

Relief and human interactions

Humans also need to learn with the many different types of relief on earth like moving rivers to cross, steep slopes to climb and soil that is hard to dig are all examples of obstacles that humans might face.

human activity mostly happens on plains. 60% of all humans live there. the flat land of the plains makes transportation and driving much easier. the soil is generally richer and betterfor farming.

humans don’t always farm on plains. they have managed to grow rice on terraces.

the millau viaduct is a simple example of human ingenuity. it spans the tarn valley in france.

Skiing was originally used as a means of transportation on snowy peaks in the winter. other sports also started just like skiing. for example canoeing and kayaking were used to cross bodies of water.