Magma is liquid rock with dissolved gas within the interior of the Earth. But when this molten rock find its way to the surface, it’s lava.
It’s when pressure builds up, volcanoes erupt. Magma spews from the planet interior to surface. Lava flows out the volcano and always goes downhill.
When gases get hot enough, they expand and explode. When lava flows on the surface, it builds new land as igneous rocks.
Not only do volcanoes spew out lava, but also water. But because water won’t sit on lava, it evaporates into a gas. Then, water vapor forms clouds.
This is why volcanoes are vital to geologists. It’s because it’s the start of the rock cycle.
Different kinds of volcanoes lock in different types magma underground. It’s the from the various types of magma that differentiate the types of volcanoes.
Igneous rocks from volcanoes
Volcanoes are the foundation for igneous rocks. Like a closed bottle of champagne, liquid rock pools in the magma chamber.
Once you pull the cork, the volcano erupts. It erupts from the expansion of gases from the mouth of the volcano.
Eventually, lava spews from the mouth. Like wax dripping down the side of a candle, igneous rocks like feldspars form.
So hot lava drips on the side of volcanoes then cools, hardens and become igneous rocks like granite. Without igneous rocks, there wouldn’t be the rock cycle.
READ MORE: How the Rock Cycle Recycles Earth’s Crust
The formation of volcanoes
Because divergent plates move apart from each other at these mid-oceanic ridges, magma flows upwards from the mantle beneath. When the lava hardens, it becomes dark igneous rock “basalt” at rift volcanoes.
When convergent plates collide, plates thrust upwards. Convergent boundaries has some of the most violent catastrophes and geology on Earth. When plates smash together, it has created chains of volcanoes.
Finally, volcanoes form at hot spot plumes. Like Hawaii, hot spot plumes rise through the mantle and melts when it reaches asthenosphere levels.
For example, the Pacific Ring of Fire is known for having one of most active chain of volcanoes in the world. This is why earthquakes and volcanoes are common in countries like Indonesia, Japan and the Philippines.
What’s the difference between magma and lava?
Today, you’ve learned that the difference between magma and lava is all about location. Lava spews out from volcanoes when it erupts. But magma is still bottled inside the volcano.
Don’t stop here though. Plate tectonics are the main mechanism that pushes plates together to form volcanoes. Read these hand-picked articles to get the whole picture of volcanoes:
From large to small, the 7 major tectonic plates include the Pacific, North American, Eurasian, African, Antarctic, Indo-Australian and South American plate.
Under the rigid layer of rock we live on, the asthenosphere is plastic and more dense. Because of its fluid properties, mantle convection can occur which is the primary mechanism for plate movement.
Plate tectonics are deceptively slow. It’s just centimeters each year. Continental drift is the idea that continents passively move due to tectonic activity
2 theories exist for the origin of water on Earth: Did comets transport water? Or was there degassing from volcanoes from rocks existing within the crust?