Answer: form at high pressures and low temperatures.
These processes are relatively local in occurrence and usually reach only the low-pressure facies such as the hornfels and sanidinite facies . Most metamorphic rock is formed by regional metamorphism in the middle and lower crust where the rock reaches the higher-pressure metamorphic facies . This rock is found at the surface only where extensive uplift and erosion has exhumed rock …
Metamorphism is the change of minerals or geologic texture (distinct arrangement of minerals) in pre-existing rocks () without the protolith melting into liquid magma (a solid-state change). The change occurs primarily due to heat pressure and the introduction of chemically active fluids. The chemical components and crystal structures of the minerals making up the rock …
Hume’s fork – Wikipedia
Amphibolite – Wikipedia
Metamorphic rock – Wikipedia
Amphibolite – Wikipedia
Amphibolite (/ æ m ˈ f ɪ b ə l aɪ t /) is a metamorphic rock that contains amphibole especially hornblende and actinolite as well as plagioclase.. Amphibolite is a grouping of rocks …
Ultramafic rocks (also referred to as ultrabasic rocks although the terms are not wholly equivalent) are igneous and meta-igneous rocks with a very low silica content (less than 45%) generally >18% MgO high FeO low potassium and are composed of usually greater than 90% mafic minerals (dark colored high magnesium and iron content). The Earth’s mantle is composed of ultramafic rocks .
Hume’s fork in epistemology is a tenet elaborating upon British empiricist philosopher David Hume’s emphatic 1730s division between “relations of ideas” versus “matters of fact.” (Alternatively Hume’s fork may refer to what is otherwise termed Hume’s law a tenet of ethics.) As phrased in Immanuel Kant’s 1780s characterization of Hume’s thesis and furthered in the 1930s by …