GEOLOGY

Detailed explanation-1: -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.

Detailed explanation-2: -Extrusive igneous rocks form when lava reaches the Earth’s surface a volcano and cools quickly. Most extrusive (volcanic) rocks have small crystals. Examples include basalt, rhyolite, andesite, and obsidian. Intrusive, or plutonic, igneous rocks form when magma cools slowly below the Earth’s surface.

Detailed explanation-3: -Most basalts are volcanic in origin and were formed by the rapid cooling and hardening of the lava flows. Some basalts are intrusive having cooled inside the Earth’s interior. Granite is an igneous rock that is composed of four minerals. These minerals are quartz, feldspar, mica, and usually hornblende.

Detailed explanation-4: -The two main types of igneous rocks are plutonic rocks and volcanic rocks. Plutonic rocks are formed when magma cools and solidifies underground. Volcanic rocks are formed from lava that flows on the surface of the Earth and other planets and then cools and solidifies.

Detailed explanation-5: -Intrusive or extrusive. Intrusive (plutonic) rocks form when magma solidifies within the crust below the surface. It usually cools slowly and produces large crystals. Extrusive (volcanic) rocks form when magma erupts onto the surface of the Earth as lava flows, and usually cools quickly producing small crystals.