A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

How are extrusive igneous rocks formed?

Best Answers

Extrusive igneous rocks, or volcanics, form when magma makes its way to Earth's surface. The molten rock erupts or flows above the surface as lava, and then cools forming rock. The lava comes from the upper mantle layer, between 50 km and 150 km below the Earth's surface. read more

Extrusive igneous rocks, or volcanics, form when magma makes its way to Earth's surface. The molten rock erupts or flows above the surface as lava, and then cools forming rock. The lava comes from the upper mantle layer, between 50 km and 150 km below the Earth's surface. When lava erupts onto the Earth's surface, it cools quickly. read more

Extrusive igneous rocks are formed by cooling lava. Since the temperature gradient between lava and Earth’s atmosphere is very big, cooling is very rapid. The second option is deemed true, which also means the third option is false. Foliations occur only in metamorphic rocks, deeming the forth option false. read more

Extrusive Igneous Rocks; Extrusive igneous rocks are formed when molten magma spill over to the surface as a result of volcanic eruption. The magma on the surface (lava) cools faster on the surface to form igneous rocks that are fine grained. Examples of such kind of rocks include pumice, basalt, or obsidian. read more

Encyclopedia Research

Wikipedia: