Metamorphic rock
Metamorphic rocks were once either igneous or sedimentary rocks but were transformed both physically and chemically under great heat and/or pressure.
Thermal/ contact - when rocks are transformed as a result of intense heat alone. It occurs in areas of volcanic activity, with magma or lava cooking the rocks it comes into contact with. Rocks formed are called aureoles.
Regional - this is when rocks are transformed as a result of both intense heat and high pressure. It occurs during folding as the result of pressure of colliding plates.
Dynamic - rocks transformed as a result of high pressure alone. It occurs when pieces if crust slip past each other in opposite directions causing deformation.
the following is a list of metamorphic rocks and their parent rocks
Marble - a coarse grained and crystalline rock that was originally limestone. Pure marble is white but different chemical compositions give variations in colour eg, serpentine gives green, carbon gives dark grey. It is mainly used for ornamental purposes eg, worktops and fireplaces. It can be found in cork (red/pink) and Connemara (green). It’s formed through thermal/contact when plates collide and the limestone is sub ducted; on entering the marble mantle, magma rises and surrounds the limestone, changing it to marble.
Quartzite - a hard, non-porous rock and erosion-resistant white or grey rock that was originally sandstone. It was crystallised after the spaces between the sand grains were filled with silica. It’s used mainly in road surfacing. It’s found at the summit of the sugarloaf.
Slate - a fine grained, dark grey or black rock that was originally shale. It splits very easily, and so is used for roofing. It’s formed through dynamic metamorphism, when shale is placed under immense pressure from destructive plates. It compresses shale into strata, forming slate. Found in Valentia