What is intrusive extrusive rock?

The two main categories of igneous rocks are extrusive and intrusive. Extrusive rocks are formed on the surface of the Earth from lava, which is magma that has emerged from underground. Intrusive rocks are formed from magma that cools and solidifies within the crust of the planet.

What are extrusive rocks for kids?

Extrusive rocks are formed when magma rises to the surface of the Earth and hardens, which forms extrusive igneous rocks. But with intrusive igneous rocks, they are formed when the magma cools and hardens below the Earth’s surface. These rocks take a long, long time to form because of the way that they are made.

How do you know if a rock is intrusive or extrusive?

Crystal Size and Texture The most obvious difference between extrusive rocks and intrusive rocks is crystal size. Because extrusive rocks cool quickly, they only have time to form very small crystals such as basalt or none at all. On the other hand, intrusive rocks grow larger crystals because they take longer to cool.

What are 4 extrusive igneous rocks?

Extrusive igneous rocks erupt onto the surface, where they cool quickly to form small crystals. Some cool so quickly that they form an amorphous glass. These rocks include: andesite, basalt, dacite, obsidian, pumice, rhyolite, scoria, and tuff.

How are extrusive and intrusive rocks formed Class 7?

Extrusive rocks are formed by the molten lava which comes out of volcanoes, reaches the earth’s surface and cools down rapidly to become a solid piece of rock. For example, basalt. When the molten magma cools down deep inside the earth’s crust, the solid rocks so formed are called intrusive rocks.

What are the examples of extrusive igneous rocks?

Types of extrusive igneous rocks include: pumice, obsidian, andesite, rhyolite, and basalt.

What are the characteristics of intrusive igneous rocks?

Intrusive rocks are characterized by large crystal sizes, i.e., their visual appearance shows individual crystals interlocked together to form the rock mass. The cooling of magma deep in the Earth is typically much slower than the cooling process at the surface, so larger crystals can grow.

Is basalt an extrusive igneous rock?

Basalts are common aphanitic igneous extrusive (volcanic) rocks. Basalts are composed of minute grains of plagioclase feldspar (generally labradorite), pyroxene, olivine, biotite, hornblende and <20% quartz.

What are the 3 types of intrusive rock?

Three common types of intrusion are sills, dykes, and batholiths (see image below).

What are extrusive igneous rocks used for?

Explanation: Extrusive igneous rocks form when magma hardens above the earth’s surface. Examples of these include pumice and basalt. Pumice is used in toothpaste and cosmetic products, while basalt is used in the construction of statues and buildings.

How are intrusive and extrusive igneous rocks alike?

Intrusive and extrusive igneous rocks are alike in that they are both formed from the cooling and crystallization of molten substance (magma and lava,…

How are intrusive rocks different from extrusive rocks?

Intrusive rocks have a coarse grained texture. 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.

Where does the cooling of an extrusive rock occur?

The rapid cooling of the extrusive igneous rock happens on the surface or very near the surface of the earth. The lava that erupts from the volcano will cool and solidify quickly in the contrasting temperature at the surface of our planet. Due to this quick cooling, the minerals in the rock do not have much time to form very large crystals.

How big is an intrusive rock in km?

The basaltic structure is 3000 meters thick and is about 65 km long. Dikes are a sheetlike body that cuts across the layers of country rocks in a roughly vertical or near vertical direction. The length and width of dikes are much larger than their thickness.

When does an intrusive igneous rock become solid?

Also called plutonic rock, intrusive igneous rock will slowly cool over many years until it becomes solid rock. With the slower cooling, the minerals that are within intrusive igneous rock will have more time to get larger in size.