Igneous and Metamorphic Rocks: Formation of Igneous Rocks

The video explains the formation of igneous rocks, both intrusive and extrusive. Intrusive rocks form when magma cools slowly beneath the Earth's surface, allowing large crystals to develop, as seen in pegmatite. In contrast, extrusive rocks form when lava cools quickly on the surface, resulting in smaller crystals, as in rhyolite. Obsidian forms so rapidly that no crystals are visible, giving it a glass-like appearance. Some extrusive rocks, like pumice, have trapped gases that create air pockets, enabling them to float.

What is the process by which magma forms igneous rock?

Evaluate responses using AI:

OFF

What distinguishes intrusive rock from extrusive rock?

Evaluate responses using AI:

OFF

How does the cooling rate of magma affect crystal size in igneous rocks?

Evaluate responses using AI:

OFF

What characteristics define pegmatite as an igneous rock?

Evaluate responses using AI:

OFF

Explain why some extrusive rocks, like pumice, can float.

Evaluate responses using AI:

OFF