» Skip to content

Earth Processes
Home » Natural Heritage » Shetland's Geology » Themes » Earth Processes

Earth Processes

Diagram to show the structure of the Earth Diagram to show the structure of the EarthZoomOur world is made up of five layers.

On the outside is a layer of gases – our atmosphere. Next comes a liquid layer of water – seas and oceans.   Below this lies the Earth’s crust which, in places, rises through the water to produce the continents and islands we recognise today.  This sits on top of an enormously deep layer of semi-molten rock – the mantle – that surrounds the Earth’s core. The core is made of metal, mainly iron, and divided into a solid inner core and a liquid outer core.  Currents circulating in the outer core generate the Earth’s magnetic field

The Earth’s crust is divided into several pieces, or plates that slide around on the upper part of the mantle.  There are two kinds of crust.  The ‘continental crust’ we live on floats high in the mantle but there is a denser, heavier crust that sits lower down.  The depressions caused by this crust fill with water to form our oceans, and we call this crust ‘oceanic crust’.

Basement rocksCalendonian mountainsShetland's ophioliteShetland's volcanoFaults