Learn More About Rocks Below...
A rock is a naturally occurring solid mixture of one or more minerals, or organic matter .There are three types of rock: Igneous, Sedimentary, and Metamorphic.
Igneous Rock is formed when magma cools deep within the earth or on the surface.
Wind and rain erodes rock and deposits rock particles in layers at the bottom of bodies of water, such as the ocean.
Layers of sediment eventually cement together forming sedimentary rock.
Heat and pressure around sedimentary rock can transform it into metamorphic rock.
Metamorphic rock is eventually melted inside the earth and turned back into magma, and the rock cycle repeats.
Igneous Rock: rocks formed by the cooling and solidifying of molten materials. Igneous rocks can form beneath the Earth’s surface, or at its surface, as lava.
Sedimentary Rock: rock that has formed through the deposition and solidification of sediment, especially sediment transported by water, ice, and wind. Sedimentary rocks are often deposited in layers, and frequently contain fossils.
Metamorphic Rock: rock that was once one form of rock but has changed to another under the influence of heat or pressure without passing through a liquid phase.
Rocks can be classified into three main types: igneous, metamorphic, and sedimentary.
Use the table below to identify the characteristics of different types of rock:
The rock cycle shows that any rock can turn into any other type of rock.
- Through the process of HEAT & PRESSURE, igneous and sedimentary rock become METAMORPHIC rock.
- Through the process of WEATHERING & EROSION, metamorphic and igneous rock become SEDIMENTARY rock.
- Through the process of MELTING, sedimentary and metamorphic rock become IGNEOUS rock.
Erosion: the process by which the surface of the earth is worn away by the action of water, wind, glaciers, and waves.
Weathering: the various mechanical and chemical processes that cause exposed rock to decompose (ie: rain, wind, freezing and melting).
Sediment: particles of rock that have been broken down by weathering and erosion.
What does a Geologist Do ? Click here to find out.
Rock Cycle Song
(Sing to the tune of "Row, Row, Row Your Boat")
Has been formed in layers
Often found near water sources
With fossils from decayers
Then there's IGNEOUS rock
Here since Earth was born
Molten Lava, cooled and hardened
That's how it is formed
These two types of rocks
Can also be transformed
With pressure, heat and chemicals
METAMORPHIC they'll become
LAYERS OF THE EARTH
Crust: The Earth’s crust is composed of oceanic crust and continental crust. Oceanic crust is the crust on the ocean floor. It is less than 10 km thick, and made of mostly basalt rock and contains the elements silicon, oxygen, iron, and magnesium. The oceanic crust moves on top of the asthenosphere because of convection currents in the hot mantle. Continental crust is the crust that contains Earth’s continents and averages about 32 km thick. Underneath mountains, the continental crust can reach a thickness of 70 km. It’s primarily made of granite rock, and contains the elements silicon, oxygen, aluminum, calcium, sodium, and potassium. The continental crust moves on top of the asthenosphere because of convection currents in the hot mantle. The crust is the least dense of all Earth’s layers.
Mantle: The mantle is the largest layer of the Earth and is located directly above the outer core. The mantle is roughly 2900 km thick and contains about 80% of the volume of the Earth. The mantle is composed mostly of the elements silicon, oxygen, iron, and magnesium. The density of the mantle increases with depth, as do temperature and pressure.
Outer Core: The outer core is about 2250 km thick. The outer core is made of the metals iron and nickel. The temperature ranges from 2200-5000 degrees Celsius, and the heat makes the iron and nickel molten, or change into a hot liquid.
Inner Core: The inner core is about 1300 km thick. The temperature of the inner core reaches 5000 degrees Celsius. It is made of iron and nickel. But unlike the outer core, the enormous pressure at this depth pushes the particle of iron and nickel so tightly together that the elements remain solid.
Layers of the Earth vidio clip below
The Earth is made of layers, each with its own distinct chemical and physical properties. Scientists use earthquakes to study the Earth’s interior.
Discuss how scientists study the structure of the Earth’s interior. Recognize that an understanding of the motion of earthquake waves can help scientists formulate hypotheses about the Earth’s interior. Compare and contrast the different layers of the Earth.
1. Physical Properties (characteristics):
As you travel from the surface of the earth towards the interior:
- Composition(what it’s made of):
Crust: solid rock
Mantle: melted rock
Outer Core: liquid iron
Inner Core: solid iron and nickel
- Major layers of the Earth(from surface to interior):
Crust Mantle Outer Core Inner Core
- Plate Movement:
The plates of the lithosphere float on the upper mantle. This part of the mantle is called the asthenosphere. The consistency of the asthenosphere is like silly putty. The asthenosphere is hot, and, like silly putty, it can flow. The movement of the plates of the lithosphere on top of the slowly moving asthenosphere accounts for the formation of many mountains and volcanoes, as well as for earthquakes.
- Mantle Structure:
The upper mantle structure is rigid and cool. The bottom mantle structure is hot and plastic-like. Movement of this part of the mantle can cause mountains and volcanoes to form.
- How are the Earth’s interior and the ocean floor related?
The ocean floor is the closest part of the surface to the inside of the Earth. Earthquake waves are studied to see how far in the core of the Earth is.
ALSO: If a boat wants to know how far down the ocean floor is, or where bumps on the bottom of the ocean are, they use sonar and then time how long the signals take to bounce back to the boat again.
*DEFINITION OF SONAR: SOUND NAVIGATION AND RANGING*
- How do earthquake waves help identify the layers of the earth?
Scientists know that P-waves can travel through solids and liquids, but S-waves can only travel through solids. Because of the variety of thickness in the Earth’s layers, scientists can detect the speed it takes for the waves of an earthquake to go through the Earth and hit the other side.
How deep have humans been into the earth?
Drilling into the Mantle (Click on the links below)
Project Mohole: First attempt to drill into the mantle in the 1960s.
A new attempt: Here is a National Geographic article about how scientists are using new technology to try again.
Kola Superdeep Borehole, Russia: A scientific drilling project in the former Soviet Union that attempted to drill as deep as possible into the Earth’s crust. The project began in 1970 and reached a final depth of 12,262 meters (40,230 ft) in 1989. It is the deepest hole ever drilled.