As the magma cools, different crystals form at different temperatures, undergoing crystallization. For example, the mineral olivine crystallizes out of magma at much higher temperatures than quartz.
The rate of cooling determines how much time the crystals will have to form. Slow cooling produces larger crystals. The small fragments are called sediments. Running water, ice, and gravity all transport these sediments from one place to another by erosion. During sedimentation , the sediments are laid down or deposited. In order to form a sedimentary rock, the accumulated sediment must become compacted and cemented together. When a rock is exposed to extreme heat and pressure within the Earth but does not melt, the rock becomes metamorphosed.
Metamorphism may change the mineral composition and the texture of the rock. Skip to main content. Rocks and the Rock Cycle. Search for:. Reading: The Rock Cycle Figure 1. Figure 3. Rock samples. Figure 7. James Hutton is considered the Father of Geology. Rocks at the surface are lying in place before they are next exposed to a process that will change them. Several processes can turn one type of rock into another type of rock.
The key processes of the rock cycle are crystallization, erosion and sedimentation, and metamorphism. Magma cools either underground or on the surface and hardens into an igneous rock. As the magma cools, different crystals form at different temperatures, undergoing crystallization. For example, the mineral olivine crystallizes out of magma at much higher temperatures than quartz. Igneous rock can form underground, where the magma cools slowly. Or, igneous rock can form above ground, where the magma cools quickly.
Notice how many time "weathering" and "erosion" green arrows appear in the above diagram? When it pours out on Earth's surface, magma is called lava. Yes, the same liquid rock matter that you see coming out of volcanoes.
Igneous rock that pours out onto the Earth's surface is called igneous extrusive , whereas igneous rock that cools beneath the surface is called igneous intrusive.
On Earth's surface, wind and water can break rock into pieces weathering! They can also carry rock pieces to another place erosion!. Usually, the rock pieces, called sediments, drop from the wind or water to make a layer.
The layer can be buried under other layers of sediments. After a long time the sediments can be cemented together to make sedimentary rock. In this way, igneous rock can become sedimentary rock. All rock can be heated. But where does the heat come from? Inside Earth there is heat from pressure push your hands together very hard and feel the heat. There is heat from friction rub your hands together and feel the heat. There is also heat from radioactive decay the process that gives us nuclear power plants that make electricity.
So, what does the heat do to the rock? It bakes the rock. Remember, all rocks are made up of mineral crystals, or pieces of other rocks made up of crystals. Baked rock does not melt, but it does change. It forms crystals. If it has crystals already, it forms larger crystals. Because this rock changes, it is called metamorphic. Remember that a caterpillar changes to become a butterfly. That change is called metamorphosis. Metamorphosis can occur in rock when they are heated to to degrees Celsius.
When Earth's tectonic plates move around, they produce heat. When they collide, they build mountains and metamorphose the rock. The rock cycle continues. Mountains made of metamorphic rocks can be broken up and washed away by streams. New sediments from these mountains can make new sedimentary rock.
The rock cycle never stops. Igneous Rocks : Igneous rocks are a type of rock formed from extremely hot 2, degrees F molten masses known as magma. Generally, magma lies about 90 miles below the surface.
In certain places, such as Yellowstone National Park, the magma is as close as 40 miles below the surface. On average, every feet you dig down into the earth, the temperature will increase about 1.
Sometimes magma forces its way up to the surface through a vent such as a volcano and spills onto the surface. This happened near Flagstaff, Arizona at Sunset Crater less than 1, years ago. Once magma comes out onto the surface of the earth it is called lava, and it cools rapidly at the surface. Extrusive igneous rocks can be distinguished by their small crystal sizes.
In all extrusive igneous rock, it is nearly impossible to detect crystals without the aid of a microscope. The faster the rock cools, the smaller the crystals. Some extrusive igneous rocks cool so quickly that they have a glassy texture. Common extrusive igneous rocks are: andesite, basalt, dacite, pumice, rhyolite, and obsidian.
Intrusive igneous rocks solidify over a period of thousands of years. This slow cooling rate allows better development of mineral crystals. Intrusive igneous rocks will have eye visible crystals and will appear coarse-grained. Igneous intrusive rocks eventually will become exposed at the surface of the earth by erosion of the overlying material. Common intrusive igneous rocks are: granite, diorite, gabbro, and peridotite. The La Sal Mountains were formed by widespread igneous activity that began about 40 million years ago.
Yes, the same liquid rock matter that you see coming out of volcanoes. On Earth's surface, wind and water can break rock into pieces. They can also carry rock pieces to another place. Usually, the rock pieces, called sediments, drop from the wind or water to make a layer. The layer can be buried under other layers of sediments. After a long time the sediments can be cemented together to make sedimentary rock.
In this way, igneous rock can become sedimentary rock. All rock can be heated. But where does the heat come from? Inside Earth there is heat from pressure push your hands together very hard and feel the heat.
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