Which of the following rocks is produced by the solidification of magna within the earth crust

Assessment: JAMB UTME - Geography - 2023 Subject: Geography

Question 1 Report

Which of the following rocks is produced by the solidification of magna within the earth crust
Answer Details
The rock that is produced by the solidification of magma within the Earth's crust is called **plutonic rock**. Plutonic rocks are also known as intrusive rocks. Magma is molten rock that is found beneath the Earth's surface. When this magma cools down slowly, it solidifies and crystalizes within the Earth's crust, forming plutonic rocks. This slow cooling process allows for the formation of large mineral crystals within the rock. One key characteristic of plutonic rocks is that they have a coarse grain texture. This means that the mineral crystals within the rock are visible to the naked eye. Examples of plutonic rocks include granite, diorite, and gabbro. In contrast, **extrusive rocks** are formed from lava that cools quickly on the Earth's surface. When lava erupts from a volcano and cools rapidly, it forms extrusive rocks. These rocks, such as basalt and pumice, have a fine-grained texture because the fast cooling does not allow for the growth of large mineral crystals. On the other hand, **sedimentary rocks** are formed from the compaction and cementation of sediments (such as sand, silt, and clay) that have been deposited by water, wind, or ice. Sedimentary rocks, like sandstone and limestone, often contain fossils and layers. Lastly, **metamorphic rocks** are formed by the transformation of existing rocks due to high temperature and pressure deep within the Earth's crust. Examples of metamorphic rocks include marble and quartzite. To summarize, plutonic rocks are produced by the slow solidification of magma within the Earth's crust, resulting in coarse-grained rocks with visible mineral crystals.

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