All Science Content

Similar Content
Rock Cycle Lesson
Rock Cycle Practice
Rock Quiz
Rock Quiz Answers
Rock Cycle Video

Vocabulary mouseover for definition

Rock A combination of minerals, usually containing one or more of htese elements: Oxygen, Silicon, Aluminum, Iron, Calcium, Sodium, Potassium, Magnesium
Mineral solid, inorganic, naturally occurring substances with a specific chemical formula and general structure.
Rock Cycle The process by which rock changes from one type to another
Magma molten material inside the volcano, and deep beneath the Earth's crust
Lava molten material running out of the volcano
Crust Outer most layer of the Earth
Mantle Layer of the Earth just beneath the crust
Metamorphic Rock Rock formed by heat and pressure, usually deep beneath the Earth's surface, although hot lava can form "contact metamorphic rock."
Sedimentary Rock Rock formed by weathered and eroded material. Also from fossils or other dead organic material.
Igneous Rock Rock formed by molten rock,such as magma or lava. Magma and lava are essentially the same, they are called so by where they are located and not really what they are made of.
Intrusive Igneous Rock Rock formed by magma cooling inside the volcano or magma chamber.
Extrusive Igneous Rock Rock formed by lava cooling on the surface of the Earth, outside the volcano.
Clastic Sedimentary Rock Rock formed by weathered debris.
Chemical Sedimentary Rock Rock formed by chemicals dissolved in solution
Organic Sedimentary Rock Rock formed by the accumulation of plant or animal debris
Foliated Metamorphic Rock Rock formed by heat and extreme pressure resulting in bands or layers

Nonfoliated Metamorphic Rock Rock formed by heatr and pressure that do not have bands or layers.

THE ROCK CYCLE

What Are Rocks?

They make up buildings, countertops and collections. They come in all shapes and sizes. They come in many different textures. They they are banded, colored, and soft, or hard. And many times, they are considered a girl's best friend. They are rocks.

Rocks are really nothing more that a combination of a few different minerals, some just one mineral. But it's these combinations that make them a great choice for building a house or giving her that "happily-ever-after" wedding band!

Although there are close to 2000 minerals that have been identified, there are 8 which are most commonly found in rocks on our planet: Oxygen, Silicon, Aluminum, Iron, Calcium, Sodium, Potassium, Magnesium. No matter what a specific rock is made of, it has one thing in common with every other rock on the planet: it is classified by how it is formed.

From every sea to shining sea and from mountain top to its valley below lies rock. Weathered soil, ocean floor, or mountain peaks that form the skyline are just rocks that represent different parts of the rock cycle.

Rock Cycle

The rock cycle is a process by which rock changes from one type to another. Rocks are classified according to how they are formed. Rocks that are formed by cooling magma or lava are called igneous rocks. Rocks that are formed by weathered particles that become compacted and cemented are called sedimentary rocks. Rocks formed by extreme heat and pressure are called metamorphic rocks.

IGNEOUS ROCK

Even though a cycle is never ending, the cycle's story has to start somewhere. Let's begin in the layer of the Earth, deep beneath the ground (crust) you walk on called the mantle. The uppermost part of the mantle is the happening place for the beginning of an igneous rock because it contains molten material or magma. The extremely hot magma (between 1300 °F to 2400 °F) from the mantle rises up through cracks in the crust because it is less dense that the rock around it and under pressure. If the magma makes it to the surface, then it becomes lava. If this molten rock cools on top of the surface, then it is called extrusive igneous rock. If it cools below the surface, then it is called intrusive igneous rock. Where the molten material cools and how fast it cools determines what type of igneous rock it is.

Sedimentary Rock

Sedimentary rock is made from other rocks, fossils, and sediments. Weathering, erosion, deposition, compaction, and cementation is the basic process for formation. There are 3 different types of sedimentary rocks: clastic, chemical and organic.

Clastic sedimentary rocks are formed from the debris of mechanical weathering.
Ex: Sandstone
Chemical sedimentary rocks form from dissolved materials in solution.
Ex: Rock salt
Organic sedimentary rocks form from the accumulation of plant or animal debris.
Ex: Coal

 Metamorphic Rock
Metamorphic rocks are rocks that are formed from extreme heat and pressure. Most metamorphic rocks are located near subduction zones deep beneath the Earth's surface. There are 2 types of metamorphic rock: foliated and nonfoliated.

Foliated metamorphic rocks are formed by heat and extreme pressure. The minerals in the rock starts to align in bands because pressure is coming mainly from one direction. Over time this can form thin sheets of rock layers. Examples of foliated rock are gneiss, slate, and mica.

Nonfoliated metamorphic rock is formed by heat and pressure, but do not form the layered look or bands. Contact metamorphism occurs when hot igneous rock comes in contact with a rock and the heat causes chemical changes in the rock altering its composition and appearance. Examples of nonfoliated rock are marble and quartzite.