Question Video: Identifying Which Term Is Not a Classification of Rock Science

Which of the following is not a classification of rock? [A] Igneous [B] Sedimentary [C] Progressive [D] Metamorphic


Video Transcript

Which of the following is not a classification of rock? (A) Igneous, (B) sedimentary, (C) progressive, (D) metamorphic.

Rocks are naturally occurring solid material substances formed from one or more minerals. Rocks are classified according to how they are formed. We’ll use this diagram to help us understand how the different types of rocks are formed. The first type of rock is made from hot molten material. This substance is called magma when it’s below the surface of the Earth and lava when it’s above the surface. When magma or lava cools and solidifies, igneous rocks are formed.

Granite is an example of an igneous rock. When rocks like igneous rocks reach the surface of the Earth, they can be weathered and eroded by rain and wind. Weathering and erosion break the rocks into smaller particles or sediment. These bits of rock and sediment are then transported, typically by air or water, and deposited into a layer. These layers build up over time as more sediment is deposited. As the layers build up, the pressure increases and the bottom layer is compacted. This increase in pressure also removes water from the bottom layer cementing the sediment together. As more layers become compacted and cemented together, sedimentary rock is formed.

Sandstone is an example of a sedimentary rock. When igneous or sedimentary rock is exposed to high temperature and pressure and the rock does not melt into a liquid, metamorphic rock is produced. An example of a metamorphic rock is marble. It is formed when limestone, a sedimentary rock, is exposed to high temperature and pressure. We can see that the three main classifications of rock are igneous, sedimentary, and metamorphic.

Therefore, the answer choice that is not a classification of rock is answer choice (C), progressive.

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