Question

How do metamorphic rocks turn into igneous rocks?

Answer 1

Hint: One of the prominent processes in geology is the rock cycle which describes the transition of three main types of rocks, igneous, sedimentary and metamorphic, over a long period. The three kinds of rocks have a primary characteristic that defines their nature. In case of igneous rocks, they are made up of solidified magma and volcanic material which seeps through existing rocks and crystallises or erupts during volcanic activity and hardens on the earth’s surface. In the case of sedimentary rocks, they result from the deposition of minerals and organic matter in layers on top of each other over a long period of time. In the case of metamorphic rock, pre-existing rocks, due to the prolonged effect of heat and pressure, change texture and minerals.

Complete answer: When metamorphic rocks are pushed deep inside the earth’s surface, they may melt due to high temperature and become magma. If the magma then seeps into cracks of pre-existing rocks in the earth’s crust and crystallises, intrusive igneous rocks are formed. If the magma erupts during volcanic activity and solidifies later, extrusive igneous rocks are formed. In a similar way, this process might take place with sedimentary and other igneous rocks themselves.

Note: Examples of igneous rocks are basalt, pumice, scoria, granite, gabbros, diorite, etc. Examples of sedimentary rocks include sandstone, conglomerate, dolomite, flint, iron ore limestone, shale, coal, etc. Examples of metamorphic rocks include anthracite, gneiss, hornfels, marble, phyllite, schist, slate, etc.