Through what processes can metamorphic rocks and igneous rock change into a sedimentary rock ?

a) cooling of lava
b) weathering,deposition, and erosion
c) cementation and compaction
d) heat and pressure

B- weathering,deposition and erosion

The correct answer is c) cementation and compaction. Let me explain how sedimentary rocks are formed and why the other processes mentioned do not apply.

Sedimentary rocks are formed through a process called lithification. This process involves the transformation of loose sediment, such as sand, silt, and clay, into solid rock. It occurs in two main steps: cementation and compaction.

Cementation is the process by which mineral particles, often carried by water, are deposited and bind the sediment grains together. These minerals act as a natural glue, binding the loose particles into a solid rock. Over time, this cementation process cements the sediment grains together, forming a sedimentary rock.

Compaction, on the other hand, is the process of squeezing the sediment particles together due to the weight and pressure of the overlying layers. As more and more sediment accumulates on top, the weight of the layers above compresses the sediment, causing the grains to come closer together. This compression further helps in the formation of a sedimentary rock.

Now let's analyze the other options and why they don't apply in changing metamorphic rocks and igneous rocks into sedimentary rocks:

a) Cooling of lava refers to the process of igneous rock formation, not sedimentary rock formation. Igneous rocks are formed when molten magma cools and solidifies, either underground or at the Earth's surface.

b) Weathering, deposition, and erosion are processes related to the breakdown and transportation of rocks and minerals. These processes contribute to the formation of sediment, which then undergoes the process of lithification to form sedimentary rocks. However, these processes do not directly change metamorphic rocks or igneous rocks into sedimentary rocks.

d) Heat and pressure are factors involved in the formation of metamorphic rocks. This process, known as metamorphism, occurs when existing rocks are subjected to intense heat and pressure, causing their minerals to recrystallize and rearrange. Metamorphic rocks can further change into other metamorphic rocks through the application of heat and pressure. However, the heat and pressure alone do not transform metamorphic rocks or igneous rocks into sedimentary rocks.

Therefore, the correct process through which metamorphic rocks and igneous rocks change into sedimentary rocks is c) cementation and compaction.

Metamorphic rocks and igneous rocks can change into sedimentary rocks through the processes of weathering, deposition, and erosion (b) as well as cementation and compaction (c).