What Is the Rock Cycle?
The stuff that rocks are made from has stayed the same, but the rocks themselves have not. Over time rocks are recycled into other rocks. Moving tectonic plates are the primary agents destroying and forming various types of rocks. The processed by which rocks are made and destroyed is called the rock cycle.
The cycle diagram below (click for larger size) shows the basic processes involved with the rock cycle.
This diagram shows both the primary and secondary processes of the rock cycle.
Credits: Original artwork by Windows to the Universe staff (Dennis Ward ).
- Sedimentary rocks are formed via weathering and transport of existing rocks, and then deposition, cementation, and compaction into a sedimentary rock.
- Igneous rocks are formed by cooling and crystallization of molten rock.
- Metamorphic rocks are formed when heat or pressure are applied to other rocks.
In addition to the primary cycle (Igneous-Sedimentary-Metamorphic), this cycle diagram includes the secondary processes that show that any
rock type can be reformed into any
other rock type. For example, a sedimentary rock can be weathered and eventually the sediments are deposited to become another sedimentary rock. And an igneous rock can be melted and cooled to become another igneous rock.
These secondary processes are often omitted from textbook illustrations. Follow this link to perform a Google image search for "rock cycle diagram." Compare the various diagrams published by the USGS, numerous textbook publishers, and other sources. If you teach the rock cycle, hows does this compare to your textbook's treatment? Feel free to discuss your findings in this week's discussion forum.
You might also be interested in:
Leaders from 192 nations of the world are trying to make an agreement about how to limit emissions of heat-trapping greenhouse gases, mitigate climate change, and adapt to changing environmental conditions....more
Climate in your place on the globe is called regional climate. It is the average weather pattern in a place over more than thirty years, including the variations in seasons. To describe the regional climate...more
Less than 1% of the gases in Earth's atmosphere are called greenhouse gases. Even though they are not very abundant, these greenhouse gases have a major effect. Carbon dioxide (CO2), water vapor (H2O),...more
Television weather forecasts in the space age routinely feature satellite views of cloud cover. Cameras and other instruments on spacecraft provide many types of valuable data about Earth's atmosphere...more
Predicting how our climate will change in the next century or beyond requires tools for assessing how planet responds to change. Global climate models, which are run on some of the world's fastest supercomputers,...more
The world's surface air temperature increased an average of 0.6° Celsius (1.1°F) during the last century according to the Intergovernmental Panel on Climate Change (IPCC). This may not sound like very...more
A factor that has an affect on climate is called a “forcing.” Some forcings, like volcanic eruptions and changes in the amount of solar energy, are natural. Others, like the addition of greenhouse gases...more