Tectonic activity and plate boundaries

• The Earth's structure and plate tectonics involve the study of the Earth's layers, including the inner core, the outer core, the mantle, the crust, and the lithosphere.
• The inner core is the hottest part of the Earth, is solid, and is made up of iron and nickel with temperatures of up to 5,500°C.
• The outer core is a liquid layer surrounding the inner core, also made up of iron and nickel.
• The mantle is the thickest section of the Earth at approximately 2,900 kilometres.
• The upper part of the mantle is called the asthenosphere, which is made up of semi-molten rock called magma.
• The crust is the surface of the Earth, forming the upper part of the lithosphere.
• The lithosphere is the outer layer of the Earth, which includes both the crust and the upper layers of the mantle.
• The lithosphere is split into tectonic plates.
• Ridge push is where the new crust formed at divergent plate margins is less dense than the surrounding crust and so it rises to form oceanic ridges.
• Sinking in one place leads to plates moving apart in other places.
• The surface of the Earth's crust found underneath large land masses is referred to as continental crust, and the surface of the Earth's crust found underneath the oceans, forming the ocean floor, is referred to as oceanic crust.
• Instead of tectonic plates moving because of the convection currents, evidence suggests it is the plates that drive the convection.
• Slab pull occurs where older, denser tectonic plates sink into the mantle at subduction zones.
• The older seafloor either side of the ridge slides away and this moves the seafloor apart – moving the tectonic plates.
• The Earth's crust is either continental close continental crust or oceanic close oceanic crust.
• The Earth's crust is broken into tectonic plates.
• As these older sections of plates sink, newer and less dense sections of plate are pulled along behind.
• Mechanisms called slab pull and ridge push are believed to move the tectonic plates.
• It was once believed that convection currents in the mantle caused the plates to move, but it is now recognised to be more complicated than this.
• The movement of the plates and the activity inside the Earth, is called the theory of plate tectonics.
• The Earth's crust is the outer layer of the Earth, a thin layer between 0 - 60 km thick, and is the solid rock layer upon which we live.