Question

How can sedimentary rocks become metamorphic rocks?

Answer 1

Hint: Rock or stone is generally caused by the solid aggregate of minerals. All the rocks that make up the crust of the earth, display some texture and structure. The various kinds of rocks are grouped under three families, namely, igneous rocks, sedimentary rocks and metamorphic rocks.

Complete answer: The word sedimentary rocks had been derived from the Latin word ‘Sedimentum’ meaning settling. Rocks are formed from the weathering, erosion and deposition and compaction of rock material through agents like wind, water, ice and chemical precipitation. This process of formation of sedimentary rocks by deposition in layers as strata, forming a structure called bedding is known as Lithification. Depending upon the mode of formation the sedimentary rocks can be classified into three major groups
- Mechanically formed sedimentary rocks are formed from the sediments of other rocks that have accumulated and bonded together over a long period of time. Examples include sandstone, shale, clay and conglomerate.
- Organically formed sedimentary rocks are formed from the remains of the living organisms. Examples include limestone and chalk.
- Chemically formed sedimentary rocks are precipitated chemically from rock solutions. Examples include common salt, potash, gypsum and dolomite.
The metamorphic rocks are formed from pre-existing igneous or sedimentary rocks which have been changed as a result of great heat and pressure. When the rocks are forced down to the lower levels by the tectonic forces and subjected to great pressure by the overlying rocks, the already consolidated rocks undergo reorganization and recrystallization bringing in the change in the nature of the rocks.

Note: Metamorphic comes from Greek words meaning “change” and “form”. Two major types of metamorphic rocks - foliated metamorphic rocks for example slate and non-foliated metamorphic rocks, for example, quartzite.