Humans use rocks for many different things – in particular, roofing and building materials. Is it possible to run out of rocks? Although we should always use natural resources carefully, it’s not likely that we’ll run out of rocks anytime soon.
Rocks go through a continuous cycle of change. Igneous rocks are made when lava or magma from a volcano hardens into rock. When the rock is exposed to air, erosion begins. Almost immediately, wind and rain weather the rocks and cause them to erode into sediment.
The sediment becomes sedimentary rock. This rock is often buried beneath the Earth’s surface, where it may become metamorphic rock. If the metamorphic rock is near magma, it may melt to become igneous rock. The entire process is known as the rock cycle.
Fun Facts about Rock Cycle for Kids
- Magma that cools under the Earth’s surface into solid rock does so very, very slowly giving it a course texture. These kinds of rocks are called intrusive.
- Liquid rock that cools rapidly after exposure to the Earth’s atmosphere are fine-grained and called extrusive. Obsidian is an example of this type of rock.
- Whatever type of rock something breaks down from it remains, no matter how small it gets. Even a grain of sand is the same class of rock it was as part of a boulder, but once the grains of sand are fused together into a larger mass again it becomes sedimentary.
- In a long term battle between rock and water, water will win every time. Water, whether through surface weathering and erosion or within the groundwater, is very effective at breaking down rocks. Water dissolves minerals and carries ions away to be used elsewhere. It also carries sediment to points where it can collect, accumulate and be buried under pressure and changed back into rock.
- Most liquid rock that makes it to the surface is generally the least dense magma in the area.
- Magma that swells up to the ocean floor is effectively working both ends of the rock cycle. The magma will cool creating a new hard rock, usually basalt. During that process the heat that is leaving the rock warms the seawater and as the warmed seawater circulates through crevices starting the breaking down and metamorphism of that rock into sediment.
Rock Cycle Vocabulary
- Lava: liquid rock at or above the Earth’s surface
- Magma: liquid rock below the Earth’s surface
- Erosion: the process of wearing away rocks
- Sediment: particles of eroded rock or plant and animal debris
Learn More All about Rock Cycle
Here’s a great video for kids all about rock cycle:
An animated cut-out that explain how rock cycle works.
Rock Cycle Q&A
Question: How hot are rocks heated when they are changed?
Answer: Rocks are heated to temperatures of 1200 degrees Fahrenheit or higher.
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