The heat melts the great depths of the rock. When magma solidifies before it reaches the earth's surface, forming so called igneous intrusions such as granite. The important criteria include their chemical composition. Silicon-rich mineral melts at a lower temperature and be separated from those that have little silicon. During solidification of igneous rocks crystallize first dark minerals which have a higher melting point, such as olivine, pyroxenes, and amphiboles. Only then solidify light components such as feldspar, muscovite and quartz. The more rock has been melted, it is rich in silica. Silicon-rich magmas are lighter and accumulate in higher levels of the Earth. Paleozoic metamorphic rocks are usually, as formed from other rocks transformation during prolonged exposure to heat or pressure. The transformation of rocks may occur, in places where two lithospheric plates. In these places rocks are subjected to great pressure and temperature. At the edge of the forest just above Rieger trail in the former quarry mined pink, medium-grained rock called Bítouchov granite. A small granite body has a surface area of ​​less than 1 km2.
Bítouchov granite quarry
The rock is so strongly deformed that it is hardly recognizable as it was originally a granite Originally albitická granite is marked by the effects of conversion so that it is known as albitický metagranit. In places weaker transition, the so-called metamorphic shadows remained the original granite building still somewhat maintained. Then you can easily recognize quartz, sodium feldspar (albite), chlorite, which originated transformation of biotite, epidote and sometimes green. The tourist bridge over Jizerou silificated so strongly that its original granular structure is lost in solid form. After which the river is so metamorphed granite that at first glance reminds phyllites and therefore it is called fylonit.
Bítouchov
Railway in Jizera canyon near Semily