The Layers of the Earth

The layers of the Earth: The core • Mainly iron, mixed with little nickel. • 5500 degrees celsius in the middle of the core •The outer core, liquid and is 2220 km thick •The inner core, solid and is 1260 km thick • The core the hottest layer of the earth The mantle • Mantle forms half of the Earth • Made of heavier rock • Top of mantle is hard but the melted rock underneath is hot and soft like soft toffee (magma). •Magma moves in circular motion • 2900km thick Temperature ranges from 500-900 degree Celsius •Thickest layer The crust • The layer you live on. • A thin layer of rock around the Earth Cracked up into many pieces. Each piece of crust is called a ‘tectonic plate’ •There are two types of crust: 1. Continental crust 2. Oceanic crust Continental drift theory - The theory that all continents were joined together and have broken up and moved over time. Evidence:​ The Apparent Fit of the Continents - They look like the pieces would fit together like puzzles Fossil Correlation- Identical fossils found in the rock on either side of the ocean Rock and Mountain Correlation- Identical rocks and mountains found on either side of the ocean Paleoclimate Data- Coal found in cold region. Glacial evidence found in warm regions too. Convection Currents - Magma in the lower mantle is heated by the core. - As it heats up the magma rises up towards the upper mantle. - Further from the core, the magma cools down. - Cool magma sinks back to the lower mantle. - As the magma moves it drags the tectonic plate above it in the same direction. Definition of convection currents: Convection currents are the circular movements of magma within the Earth’s mantle caused by heat from Earth’s core. Why Do Convection Currents Occur? ● The Earth’s core gives intense heat, which warms the magma in the mantle. ● As magma heats up, it becomes less dense and rises toward the Earth's crust. ● When it cools near the crust, it becomes denser and sinks back down. ● This creates a continuous circular movement called a convection current. What Effects Do They Have? ● Convection currents drive the movement of tectonic plates on the Earth’s surface. ● These movements can cause earthquakes, volcanic eruptions. Volcanos found mostly in linear pattern, fiund around the edge of the Pacific Plate