Igneous rocks:formed by molten magma which is pushed up to the surface.Contains interlocking crystals.Two types>extrusive&intrusive.
E.G.Granite and basalt.
Sedimentry rocks:formed from layers of sediment and dead matter.Also be formed when water evaportes and leaves a dissolved solid.Layers are cemented together by other materials. Most fossils are formed in sedimentry rocks.
E.G. limestone, chalk and sanstone.
metamorphic rocks:these are the result of heat and increased pressure exerted on existing rocks over long periods of time. They may have really tiny crystals and some have layers.
E.G.marble, slate and schist.
THE EARTY'S STRUCTURE
-solid inner core(iron and nickel)
-liquid outer core(iron and nickel)
The earths surface
tectonic plates which are less dense than the mantle.
On the plate boundaries volcanoes and earthquakes occur.
THE EVOLUTION OF ATMOPSHERE
volcanoes gave out steam and CO2.
volcanoes gave out steam and CO2.- the earths surface was originally molten for many millons of years.Finally is cooled and a thin crust formed, volcanoes kept erupting, releasing carbon dioxide, steam and ammonia.early atomsphere mostly CO2 and water vapour later formed the oceans.
green plants envolved and produced oxygen.
CO2 dissolved into the oceans. Green plants started to evolved.Nitrogen gas was put into the atmosphere- it formed ammonia reacting for oxygen and was released by denitrifying bacteria.
ozone layer allows evolution of complex animals.
the build up of oxygen in the atmosphere and killed off early organisms= more complex organisms.oxygen=ozone layer.which blocked harmful rays=more complex orgainisms.