Continental plates
The earth may be divided roughly into three layers: solid crust, mantle and a core. The crust of the earth is divided into continental/oceanic plates. The plates float on top of the mantle and may drift due to its movements. As the plates drift, they collide, move sideways or drift apart, as on the Mid-Atlantic ridge.

Mid-Atlantic ridge 
Kortagrunnur.jpgThe mid-atlantic ridge reaches almost from the Antarctic to the North pole, and is formed on the edges of continental plates that are drifting apart. Therefore volcanic activity is high on the ridge. The area where Iceland is now has been especially active, one of the so-called “volcanic hot spots” of the world. The “Ridge” cuts through Iceland in the so-called “volcanic belt”. Therefore, the west part of Iceland belongs to the North American plate while the east part belongs to the Eurasian plate. The plates drift away from each other at the speed of 1 cm/year, -theoretically enlarging Iceland by 2 cm/year.

Major rock types
Iceland is very young on geological scale. The oldest rock formations are about 16 million years old. The majority of Icelandic rocks are of igneous origin, mostly basalt. Sedimentary- and plutonic rocks such as granite are rare. 

Minerals and metals
Iceland is very poor of metals, but due to high volcanic activity, it is rich of crystallised minerals such as zeolits and Iceland spar. When water runs through the bedrock, it dissolves minerals. Crystallization occurs when the water runs through holes and cavities in the bedrock, and if the space is enough, the crystals can become quite large. Temperature, pressure and trace materials may affect the structure and colour of the crystallizing minerals, resulting in a totally different structure of the same mineral such as SiO2.