Earth’s interior layers. The major layers of the Earth consist of the crust, mantle, outer core and inner core.

INNER CORE The core is composed mainly of iron and nickel. In the inner core, iron and nickel are solid.Although the inner core is very hot, pressure from the weight of the rest of the Earth doesn’t allowed the material to melt. Iron’s normal temperature of melting is 15350C, but in the earth inner core it could stand 40000C with no melting.

This electrical current powers the earth’s magnetic field. OUTER CORE. Because less weight is exerted on the outer core, the pressure is less there, so iron and nickel present here in liquid state. The molten outer core flows at the very slow rate which means electrons from the metals produce an electrical current. This electrical current powers the earth’s magnetic field.

The mantle is composed of hot iron-rich silicate rocks. Flow in the mantle occurs as convection currents; hot material in the mantle rises, cools and then sinks. Mantle is elastic which means it behave in plastic manner.

THE CRUSTAL SURFACE. CONTINENTAL CRUST – is between 20 and 60 km thick. It is composed of granitic rocks, which are less dense than basaltic rocks of the oceanic crust. So, most of continental crust is above sea level. OCEANIC CRUST - is only about 10 km thick. It is composed of basaltic rocks, which are more dense than granitic rocks of the continental crust. So, oceanic crust is below sea level.

Composition of the Earth.

THE THEORY OF PLATE TECTONICS The framework explains how and why the surface of the earth constantly changes is called theory of plate tectonic. The theory states that the earth’s outer shell, the lithosphere is divided into eight large plates. Because each plate moves as a single unit, the interiors of the plates are generally stable. All major activity such as earthquake or volcano occur along the plate boundaries.

Information from USGS: http://earthquake.usgs.gov/recenteqsww/

DIFFERENT TYPE OF BONDARIES DIVERGENT PLATE BOUNDARIES- plates are moving away from each other. Very active volcanically due to the rising of magma. (Mid-Atlantic Ridge) CONVERGENT PLATE BONDARIES- plates are coming together. The regions of plate collision are regions of great mounting buildings. (Andes, Himalayas, Sierra Nevada)

Oceanic – Oceanic Convergence Collision between two oceanic plates can result in the prosses when one plate bends and descends beneath the other to produce deep oceanic trench. (Marianas Trench) Oceanic – Continental Convergence When an oceanic plate and a continental plate converge, the denser oceanic plate is subducted beneath the less dense continental plate.A deep ocean trench is formed and magma is generated. (Andes) Continental – Continental Convergence. The collision between continental plates has produced some of the most famous mountain ranges. (Himalayas, European Alps, Appalachian)

ROCKS AND MINERALS MINERALS are the building blocks of rocks, and elements, in turn, are the building blocks of minerals. A mineral is defined as a naturally formed, inorganic, crystalline solid, composed of an ordered arrangement of atoms with specific chemical composition. Of the known 112 elements, 92 occur naturally in the earth’s crust and combine to make 4000 different minerals.

ROCK TYPES IGNEOUS ROCKS are formed by the cooling and crystallization of hot, molten rock – magma. The word igneous means “formed by fire”. Igneous rocks make up about 95% of the Earth crust. Basalt and granite are common igneous rocks. SEDIMENTARY ROCKS are formed from pieces of other rocks (sediments) carried by water, wind, or ice. Sedimentary rocks are easy to find on the ground beneath our feet – the uppermost portion of Earth crust. Sedimentary rocks cover more than two-thirds of the Earth’s surface. Sandstone, shale, and limestone are common sedimentary rocks. METAMORPHIC ROCKS are formed from older, preexisting rocks (igneous, sedimentary, or metamorphic) that are transformed by high temperature, high pressure, or both – without melting. The word metamorphic means “changed in form”. Marble and slate are common metamorphic rocks.

ROCK CYCLE

MINERALS Silicates Nonsilicates Carbonates Sulfates Clay Minerals Oxides Sulfides Ferromagnesian Phosphates Halides Nonferromagnesians Native Elements