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Metamorphic rocks are formed when existing rock is transformed physically or chemically at elevated temperature, without actually melting to any great degree. The importance of heating in the formation of metamorphic rock was first noted by the pioneering Scottish naturalist, James Hutton, who is often described as the father of modern geology ...
A rock structure can be created in any rock type or combination: Igneous rocks are created when molten rock cools and solidifies, with or without crystallisation. They may be either plutonic bodies or volcanic extrusive. Again, erosive forces sculpt their current forms. Metamorphic rocks are created by rocks that have been transformed into ...
The importance of heating in the formation of metamorphic rock was first recognized by the pioneering Scottish naturalist, James Hutton, who is often described as the father of modern geology. Hutton wrote in 1795 that some rock beds of the Scottish Highlands had originally been sedimentary rock , but had been transformed by great heat.
Igneous rocks can be seen at mid-ocean ridges, areas of island arc volcanism or in intra-plate hotspots. Metamorphic rocks once existed as igneous or sedimentary rocks, but have been subjected to varying degrees of pressure and heat within the Earth's crust. The processes involved will change the composition and fabric of the rock and their ...
Gneiss, a foliated metamorphic rock. Quartzite, a non-foliated metamorphic rock. Foliation in geology refers to repetitive layering in metamorphic rocks. [1] Each layer can be as thin as a sheet of paper, or over a meter in thickness. [1] The word comes from the Latin folium, meaning "leaf", and refers to the sheet-like planar structure. [1]
A metamorphic facies is a set of mineral assemblages in metamorphic rocks formed under similar pressures and temperatures. [1] The assemblage is typical of what is formed in conditions corresponding to an area on the two dimensional graph of temperature vs. pressure (See diagram in Figure 1). [1]
Mylonite – Metamorphic rock – A metamorphic rock formed by shearing; Metaconglomerate - A type of metamorphic rock formed through the recrystallization of conglomerates; Metapelite – Metamorphic rock – A metamorphic rock with a protolith of clay-rich (siltstone) sedimentary rock
The rocks are 70 percent plutons and 30 percent supracrustal formed between 1.765 and 1.4 billion years ago in the Proterozoic, based on uranium-lead dating. All of the rocks more than 1.65 billion years old show evidence of metamorphism ranging between greenschist and amphibolite grade on the sequence of metamorphic facies.