Rocks can form in a variety of ways. Igneous rocks form from magma (molten rock) that has either cooled slowly underground (e.g., to produce basalt) or cooled quickly at the surface after a volcanic eruption (e.g., igneous).

PHYSICAL GEOLOGY

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Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]

A	TRUE
B	FALSE
C	Either A or B
D	None of the above

Explanation:

Detailed explanation-1: -intrusive rock, also called plutonic rock, igneous rock formed from magma forced into older rocks at depths within the Earth’s crust, which then slowly solidifies below the Earth’s surface, though it may later be exposed by erosion.

Detailed explanation-2: -Igneous rocks contain randomly-arranged crystals. If the magma cools quickly, the crystals will be large (coarse grained). If the magma cools slowly, the crystals will be small (fine grained). Because igneous rocks are formed from molten rock, they do not contain fossils.

Detailed explanation-3: -Intrusive rocks are formed from magma that cools and solidifies within the crust of the planet.

Detailed explanation-4: -Extrusive, or volcanic, igneous rock is produced when magma exits and cools above (or very near) the Earth’s surface. These are the rocks that form at erupting volcanoes and oozing fissures.

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