Which is needed to turn an igneous rock or sedimentary rock into a metamorphic rock?
A. heat and pressure
B. melting and cooling
C. freezing and cementation
D. erosion and depositon
A. heat and pressure
The correct answer is A. heat and pressure. To turn an igneous rock or sedimentary rock into a metamorphic rock, both heat and pressure are required. These intense forces cause the minerals within the rock to recrystallize, leading to the formation of a new rock with different characteristics.
To determine which is needed to turn an igneous rock or sedimentary rock into a metamorphic rock, we can analyze the options given:
A. Heat and Pressure: This is the correct answer. Metamorphic rocks are formed when existing rocks, such as igneous or sedimentary rocks, undergo significant changes due to heat and pressure. These changes occur deep within the Earth's crust, where the rocks are subjected to high temperatures and immense pressure, causing their minerals and structures to rearrange.
B. Melting and Cooling: This process refers to the formation of igneous rocks, where existing rocks melt and then cool down to solidify. It is not the process by which a rock transforms into a metamorphic rock.
C. Freezing and Cementation: This refers to the process of sedimentary rock formation, where loose sediment particles are compacted and cemented together by natural processes. It is not the process by which a rock becomes metamorphic.
D. Erosion and Deposition: This process refers to the transportation and accumulation of sediments by wind, water, or ice, leading to sedimentary rock formation. It is not directly related to the transformation of rocks into metamorphic rocks.
In conclusion, the correct answer is A. Heat and Pressure.