From Magma to Magma: The Rock Cycle

By Irum Naz

Magma is basically the molten material inside the earth, and when it comes out, we call it lava.
You may not have heard about magma but you would have heard about lava for sure. Both are actually the same thing, the only difference is where they are. Inside is magma, outside is lava.

When that hot, molten material cools down, the hot liquid turns into a hard solid, and this solid is an igneous rock. This is how the first rocks on Earth were made. If it cools down fast outside, the rock becomes small-crystalline, and if it cools down slowly inside, it becomes big-crystalline.

Then, with the passage of time, igneous rocks and other rocks break into tiny sediments due to weathering, such as wind, rain, and extreme temperature changes. Even the sun’s heat in the day and cold at night can crack the rocks slowly.

These broken pieces, including parts of other rocks and sometimes fossils of animals and plants, are transferred from one place to another by air and water. This moving of sediments is called erosion. Rivers carry them far away from where they started.

These sediments reach near a river, lake, or sea and collect together in basins. They settle down layer by layer. The bottom layers get heavier as more layers come on top.

Water and sediments in that basin for many years get pressed together and combine into sedimentary rocks. The water squeezes out and minerals act like glue, so the loose sediments become hard rock. You can often see layers in sedimentary rocks.

When sedimentary rocks, igneous rocks, or other rocks go deep under the earth, the high temperature and pressure for several years change them into another rock called metamorphic rock. They don’t melt at this stage; they just change form. Their shape, color, and hardness all change inside.

After more years pass, these rocks are buried deeper into the earth with the passage of time, and inside the earth, due to very high temperature, they melt into magma again. And then the whole cycle starts again from the beginning.

It’s hard to decide whether there is magma because of rocks or there are rocks because of magma.