EXPLORING THE EARTH Lesson 1

EARTH IS COMPOSED OF SEVERAL LAYERS in the order from the outside towards the inside:

THE CRUST 1: On the outside is the relatively cold crust. Understanding the surface of our Earth is difficult without first understanding the interior, or inside of the Earth. This is because everything that is on the outside, has been formed by the enormous heat, and forces that exist on the inside. The crust of the Earth is composed of a great variety of igneous, metamorphic, and sedimentary rocks.

THE CRUST 2: The boundary between the crust and mantle is conventionally placed at the Mohorovičić discontinuity, a boundary defined by a contrast in seismic velocity. The crust occupies less than 1% of Earth's volume.

THE CRUST 3: The oceanic crust is different from continental crust. The oceanic crust is formed from 5 km to 10 km thick and consists mainly of basalt and gabbro . The continental crust is typically from 30 km to 50 km thick and is mostly composed of rocks less dense than the oceanic crust . Some of these less dense rocks , such as granite , are common in the continental crust , but rare to absent in the oceanic crust .

THE MANTLE: The mantle is one of the three main layers of the Earth. It lies between the innermost layer, the core, and the thin outermost layer, the crust. The mantle consists of hot, dense, semisolid rock and is about 2,900 kilometers

THE MANTLE 2: MANTLE is divided in two zones: Lithosphere. The thin outermost shell of the upper mantle is similar to the crust, though cooler and more rigid. Together with the crust, this layer is called the Earth’s lithosphere. Asthenosphere is a layer of more fluid mantle lithosphere

THE MANTLE 3: THE CONVECTION CELL: Mantle convection is the slow creeping motion of Earth's solid silicate mantle caused by convection currents carrying heat from the interior of the Earth to the surface. The convection of the mantle are behind THE PLATE TECTONICS

THE CORE 1: the core is divided into the inner core and outer core The outer core is molten...and so hot it could be as fluid as water. Its motions create Earth's dynamic magnetic field. The inner core is under such immense pressure that it is solid metal.

THE CORE 2 The Earth's inner core is the Earth's innermost part and according to seismological studies, it is a primarily solid ball with a radius of about 1220 kilometers, It is believed to consist primarily of an iron–nickel alloy and to be approximately at 5700 K The Earth's core is a liquid layer about 2,300 km thick composed of iron and nickel that lies above Earth's solid inner core and below its mantle. Its outer boundary lies 2,890 km beneath Earth's surface. The transition between the inner core and outer core is located approximately 5,150 km beneath the Earth's surface.

Schematic view of the interior of Earth 1. continental crust 2. oceanic crust 3. upper mantle 4. lower mantle 5. outer core 6. inner core A: Mohorovičić discontinuity B: Gutenberg discontinuity C: Lehmann discontinuity

The Earth’s structure

The Earth a planet made in layers:

Activity: Links: https://www.youtube.com/results?search_query=Earth%27s+interior+lesson+1 https://www.youtube.com/watch?v=aY6SG7GPAlo https://www.youtube.com/watch?v=N9ncfAsmiSg The end