The area affected by the contact of magma is usually small, from 1 to 10 kilometers. Contact metamorphism produces non-foliated rocks without any cleavage rocks such as marble, quartzite, and hornfels. In the diagram above magma has pushed its way into layers of limestone, quartz sandstone and shale. The heat generated by the magma chamber has changed these sedimentary rocks into the metamorphic rocks marble, quartzite, an hornfels.
Regional Metamorphism occurs over a much larger area. This metamorphism produces rocks such as gneiss and schist. Regional metamorphism is caused by large geologic processes such as mountain-building. These rocks when exposed to the surface show the unbelievable pressure that cause the rocks to be bent and broken by the mountain building process.
Regional metamorphism usually produces foliated rocks such as gneiss and schist. Dynamic Metamorphism also occurs because of mountain-building. These huge forces of heat and pressure cause the rocks to be bent, folded, crushed, flattened, and sheared. Metamorphic rocks are almost always harder than sedimentary rocks. They are generally as hard and sometimes harder than igneous rocks.
They form the roots of many mountain chains and are exposed to the surface after the softer outer layers of rocks are eroded away. Many metamorphic rocks are found in mountainous regions today and are a good indicator that ancient mountains were present in areas that are now low hill or even flat plains.
Metamorphic rocks are divided into two categories- Foliates and Non-foliates. Foliates are composed of large amounts of micas and chlorites.
These minerals have very distinct cleavage. Foliated metamorphic rocks will split along cleavage lines that are parallel to the minerals that make up the rock.
Slate, as an example, will split into thin sheets. Foliate comes from the Latin word that means sheets, as in the sheets of paper in a book. Silt and clay can become deposited and compressed into the sedimentary rock shale. The layers of shale can become buried deeper and deeper by the process of deposition.
Deposition is the laying down of rock forming material by any natural agent wind, water, glaciers over time. Because these layers are buried, temperatures and pressures become greater and greater until the shale is changed into slate.
Slate is a fine-grained metamorphic rock with perfect cleavage that allows it to split into thin sheets. Slate usually has a light to dark brown streak. Slate is produced by low grade metamorphism, which is caused by relatively low temperatures and pressures. Slate has been used by man in a variety of ways over the years. One use for slate was in the making of headstones or grave markers. Slate is not very hard and can be carved easily. The problem with slate though is its perfect cleavage.
The slate headstones would crack and split along these cleavage planes as water would seep into the cracks and freeze which would lead to expansion. This freeze-thaw, freeze-thaw over time would split the headstone. Today headstones are made of a variety of rocks, with granite and marble being two of the most widely used rocks.
Slate was also used for chalk boards. The black color was good as a background and the rock cleaned easily with water. Such conditions fuse the quartz grains together forming a dense, hard, equigranular rock. What does quartzite turn into? Quartzite, sandstone that has been converted into a solid quartz rock. Unlike sandstones, quartzites are free from pores and have a smooth fracture; when struck, they break through, not around, the sand grains, producing a smooth surface instead of a rough and granular one.
What rock becomes quartzite? Quartzite is composed of sandstone that has been metamorphosed. Quartzite is much harder than the parent rock sandstone. It forms from sandstone that has come into contact with deeply buried magmas. Quartzite looks similar to its parent rock. Is quartzite and igneous rock?
Quartzite is a compact, hard, nonfoliated, medium to coarsely crystalline, and almost mono mineral metamorphic rocks with granoblastic texture. The pure quartzite forms from the quartz-rich sedimentary rocks, such as, pure sandstone, siltstone, and hornfels. The quartzite is pressed down into the mantle and melts.
The quartzite becomes part of the magma and is ready to be pushed up, crystallizing as basalt or granite. Clearer, more vibrant, and unbroken specimens are the most valuable quartz. Those rocks can be metamorphic, sedimentary, or igneous igneous rocks are formed when magma, or molten rock, cools, either inside the earth or on the surface.
Beneficial Features: Quartzite is a decorative stone which is used for kitchen countertops, to cover walls, as roofing tiles, in flooring, and for stair steps. Quartzite is extremely popular due to its marble-like appearance and granite-like properties, which make it an ideal choice to be used in kitchens.
Even though quartzite is extremely hard it is still not scratch-proof, so we still recommend using cutting boards. The biggest downside you will see with quarzite is the tendancy for etching in different parts of the slab.
This etching can be caused by acids and other common kitchen chemicals. The way to tell a quartz sandstone from a quartzite is when you break a quartzite, the fracture will cut right through the quartz grains.
With a quartz sandstone, it is easier to break around the grains than through them. Because quartz is stable over a wide range of pressure and temperature, little or no new minerals form in quartzite during metamorphism. Instead, the quartz grains recrystallize into a denser, harder rock than the original sandstone. These smaller pieces of rock such as sand, silt, or mud can be deposited as sediments that, after hardening, or lithifying, become sedimentary rocks.
Extreme pressure from burial, increasing temperature at depth, and a lot of time, can alter any rock type to form a metamorphic rock. If the newly formed metamorphic rock continues to heat, it can eventually melt and become molten magma. When the molten rock cools it forms an igneous rock.
Metamorphic rocks can form from either sedimentary or igneous rocks. The sedimentary particles from which a sedimentary rock is formed can be derived from a metamorphic, an igneous, or another sedimentary rock. All three rock types can be melted to form a magma. Thus, the cycle has continued over the ages, constantly forming new rocks, breaking those down in various ways, and forming still younger rocks. Rocks at the surface of the earth range in age from over three billion years old to a few hundred years old.
Igneous rock can change into sedimentary rock or into metamorphic rock. Sedimentary rock can change into metamorphic rock or into igneous rock. Metamorphic rock can change into igneous or sedimentary rock. Igneous rock forms when magma cools and makes crystals. Magma is a hot liquid made of melted minerals.
The minerals can form crystals when they cool. 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. Caldera explosions erupted thousands of cubic miles of volcanic rocks from several locations.
Volcanoes spewed ash and lava.
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