Rocks Chapter 4Party like a rock

Part(y) 2By: Tamar (Tom) and Jerry

Rock History

• Rocks have been an important resource since before we were on this planet. We used these rocks to create tools like, arrowheads, spears, knives, scrapers, and axes. Some have helped us survive and develop early civilizations. They have even provided us information about early life forms.

Rock Cycle

The three main types of rock are igneous, sedimentary, and metamorphic. All of these are part of the rock cycle.

Sedimentary Rock

This rock is formed by sediments being compacted and cemented together. It takes weathering and erosion of any other rock to create this.

Stratification

Regular layering of sedimentary rock. It is the most characteristic feature of the rock.

The Process of Layering

Strata

Layers of sedimentary rock that form from deposition of sediments. This is the most noticeable feature. The Grand Canyon is the primary example.

Layering

Metamorphic Rock

Forms previous rock being heated and pressurized deep underground. They can even change into another type of metamorphic rock.

Foliated and Non-Foliated

• Foliated metamorphic rocks are composed of minerals that align together by pressure. An example could be that it looks like pages in a book.

• Non-Foliated has no distinct pattern. They are usually made up of one ore or just a few minerals. Marble and quartzite are good examples.

Igneous Rocks

It forms from the cooling of magma. When magma solidifies it creates the rock. Cooling rate determines the crystal size.

Magma is underground molten rock. Lava is the above ground magma.

Intrusive and Extrusive

Intrusive is when magma cools beneath the Earths surface. It results in a coarse grain texture. They are named by the way they push into the surrounding rock.

Extrusive forms on the surface of the Earth. It is usually volcanic rock (party like a volcano, I make it rain rocks). These have small crystals.

Composition

Composition is the minerals that make up a rock. An example would be made mostly of quartz would be similar to quartz.

Texture

Texture is determined by the shape, position, and size of the grains that make it up. When small grains bond together it is fine grained. When large grains form together it is coarse grained.

Summary

Rocks come in many different shapes, sizes, and forms. They have been a crucial part of human life since the very beginning.