Rocks and Rock Cycle


Sedimentary Rock

Sedimentary rock is rock that has been eroded into sediments, which then is pressed together into layers. Fossils, fossil fuels, and other objects, are preserved better and have little distortion in these types of rocks.

A specific rock, shale, has a lot of oil in it. If you could find a cheap way to make it yield the oil, it would make you one rich person.

Fun Fact: The precious gem, opal, mainly forms in sedimentary rock, where groundwater is rich in silica.

Igneous Rock

Igneous rock is where a rock is melted in high temeratures (in the mantle) and turns into magma. Then, it is either erupted out of a volcano, or flows out of a fault is the crust, which then cools into an igneous rock.

Obsidian is an igneous rock, and, does not have any crystal formation; it will keep accepting pressure until it shatters, it will not break like other rocks.

Fun Fact: Obsidian, a type of igneous rock, is used as surgeon blades because, "it traumatizes the tissue less." However, only some surgeons use it.

Metamorphic Rocks

Metamorphic rock is formed while under extreme heat and pressure. It is pressed and pressed, until finally it becomes a metamorphic rock.

One type of rock is quartzite, which is one of the hardest and resistent rocks out of them all. Because of it's hardness, it is used as a railway ballast.

Fun Fact: Quartzite is formed mainly from teh sedimentary rock, sandstone.

The rock cycle

As you can see from the picture below, the rock cycle is never ending and any form of rock can change into another type. The rock cycle is simple yet complex, because conditions have to be just right for new rocks to form.
The Rock Cycle video (from Learning About Rocks and Minerals Series) by Visual Learning Systems