These are dynamic,
regional and contact metamorphic rocks.
Metamorphics - Pressure
Mylonite. By Dave
Schumaker via Flickr.com
Dynamic metamorphics are the rocks that have been experiencing dynamic pressure.
They have been stretched or flattened, maybe twisted when large scale
movements happen in the Earth's crust and different rock masses are
forced over each other and crush each other as they come into
contact. These are the rocks with some impressive foliations.
Metamorphics - Temperatures
Skarn. By Maggie via Flickr.com
are mainly affected by hot
temperatures and very little by pressures.
They have therefore got no foliation or "schistosity". These rocks
and fulgurite. There
are also some rocks that can be
and contact metamorphics. They include marble,
eclogite and amphibolite.
Metamorphics - both Pressures and
the rocks that have
texture which break along the layers (except gneiss). They are formed by both
increasing pressuresand temperatures.
rocks include slate, phyllite, schist, gneiss, granulate and
migmatite. At low pressures and temperatures, the sedimentary
rock shale forms slate.
With increasing pressures and temperatures,
are formed. Each
stage also have their own
mineral composition. Shale contains clay minerals, while chlorites are
common in slate; quartz and muscovite are common in phyllite; garnet
and biotite are common in schist; and gneiss is known for minerals like