The structure of the earth
The lithosphere - is the outer layer of earth, it is cold, rigid and is made up of the crust and the top part of the mantle - It is made from tectonic plates that are less dense than the mantle below - The crust is too thick to drill, so most of the info about the Earth is collected from seismic waves produced by earthquakes and man-made explosions - more of the earths structure - the mantle is the zone between the core and the crust - at the suface it is cold and rigid, but lower down it is hot and non-rigid and can move - the earths core transfers energy so the temperature of the mantle gets hotter as you get deeper - Convection currents are what made the plates move slowly - the Oceanic crus is thicker than the continental crust - Plate tectonic theory - this is where mosts scientists now accept that Africa and South America was once one land mass - this know this because of fossils, land shape and rocks. Magma and rocks - Magma rises up through the earths crust - this can cause volcanoes - Magma can have different types of composition dependant on the type of eruption - Geologists study volcanes - they can predict europtions, but it is not 100% accurate - different types of igneous rock are made from lava - depending on how quickly or slowly it cools - Iron rich basalt rock comes from runny lava in slower eruptions - rhyolite rock comes from thick lave in explosive eruptions.
Raw materials - some raw materials used to make construction are found in the earths crust - (clay/bricks - limestone & clay/cement - sand/glass - iron ore/iron - aluminium ore/aluminium - Hardness is compared by rubbing two materials together . granite is harder than marble and marble is harder than limestone Rock hardness -limestone is a sedimentary rock and is soft - marble is metamorphic and is made from limestone that has been changed by heat and pressure - granite is made from magma cooling and hardening the interlocking crystals make it very hard. Cement & Concrete - thermal where one substance breaks down on heating to give at least two new substances.