These happen to be so far exempt from this cycle and a perfect melting. After several hundred million years the mountain building rocks are moved up again to the surface. They are used by the geologists for an analysis to detect which mineral components are included in the rock.
How old are they, how strong are unrolled individual grains of which average size?
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Are they in the first or repeated time in the cycle? What kind of stratification can be seen in the deposit? This already makes a good picture. It is easy of course to examine the past using the witnesses of past time, the numerous fossils of plants and animals. This is possible back at least million years. Finally, experienced geologists can actually analyze the rock and create an approximate sketch of the geological conditions in the initial ablation area over a period of several million years.
Gravity, wind, water and glaciers move the weathered debris and store it. For example: Sandstone. During the storage so-called loose sediments are created. This is called diagenesis.
The result is a hard sedimentary rocks, sedimentites. Chemical sediments occur when water-soluble components are transported by rivers into the sea. There it comes to new reactions, respectively when the water evaporates and the minerals are deposited. For examples: rock salt or limestone.
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Biogenic sediments are deposits of organogenic materials shells of shellfish or dead plants. For example, limestone, coal, amber. Metamorphic rocks are formed from pre-existing rocks by transformation, metamorphosis into a more or less solid state. This can originate in sediment, such as lime, which is converted to marble, or this may originate from igneous, such as granite, which is converted to gneiss.
Analog to this slate changes to phyllite or mica schist. If the process involves not only metamorphic processes but also partial melting of the rock, this results in migmatites or Anatexites. Igneous rocks are formed during cooling and solidification of molten rock, whether it is magma or lava.
This can take place either in the earth itself, for example plutonic rocks like gabbro or granite or it happens on the surface, for example as volcanic basalt, rhyolite, andesite. Plutonic rock , namely Plutonite rises by slow cooling in a great depth in the lower crust or upper mantle and under high pressure.
Thereby large crystals are formed, it will not have gas-filled cavities. An example is granite.
Igneous material gets to the surface as volcanic lava, where it cooles rapidly. Therefore, only microscopic crystals form and the rocks may have cavities. One example is basalt. If it is cooled so rapidly that no crystallization can take place, volcanic glass, obsidian, is created. World famous such as "Suttrop crystals", popularly known as "diamonds". The quartz family also includes agates with its shape and color symphony.
It is a microcrystalline variety of the mineral quartz. Striking the agate is its beautiful, drawing lane due to rhythmic crystallization. Rock crystal in the usual form is also represented in our reef limestone. And there is something very special, when it encounters here even in cubic form. The standard mineral is of course the calcite, which occurs for example in the shape of the Skalenoeder or the Rhombohedron. Somewhat rare, but also found here is barite.
Colored accents are set by the various ore minerals: In green - malachite, in blue - the Azurite In black - the hematite in Silvery - galena In yellow to brown - the limonite, in red - the iron minerals partly-greasy liquid and as the Hematite good dye for cave paintings. Rock or reef-building corals produce massive coral benches and coral reefs. Behind the reef in calm waters corals grow and settle in reef forming sediments.
On their dead shells new generations settle and form gradually a growing Limelayer. The layer thickness of the lime had reached several hundred meters. Calcification involved sponges, corals, stromatoporoids and brachiopods. The lighting must be sufficient.
Therefore corals grow only up to 70 meters water depth. And the water must be very clean. Limestone is sedimentary rock, which consist predominantly of the chemical calcium carbonate CaCO3 in the form of the minerals calcite and aragonite. Limestone is an extremely variable rock, in terms of its formation and its properties, the appearance and economic usability. The Warstein Mass Limestone is indeed caused by a coral reef. The original form of the carbonate shells can be seen for example in the local caves and on smooth walls still evident as the brachiopods Stringozephalus Burtini.
While coral lime and other reef limestones already form quite solid limestone, other Fossil lime first passes through a diagenetic consolidation. For example in the formation of Mass-limestone. By subsequent recrystallizations reef limestones may also change significantly.
Figure 1 million years ago, our land mass was located at the place, where now Tasmania is located. So about 20, km apart from the present site. Figure 2 The development of the reef began in the age of Devon, about million years ago. North Eifel and Sauerland at the time were placed in a shallow water south of the Equator and thus south of the large "Old Red" - continent. Here were ideal growing conditions and extensive reef-complexes developed, today ranging from the Harz-mountains to the Eifel.
Figure 3 million years ago, our continent was moved closer to the equator in subtropical zones.
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Our area was still slightly affected under the sea. Picture 4 Then in Devon, close to the warm equatorial regions, our land was lifted into shallow waters and our coral reef begun growing. Now conditions fit for everything: water depth, water temperature and cleanliness.
Figure 2 , now the lowering of the sea floor increased to so much that the reef growth could not keep pace, and it drowned in dark water in depths over 70 meters. This then started the overlay by sediments, increasingly burying the descending riff in another 60 million years, finally about meters underneath. In Upper Carboniferous, around million years ago, we got a bit north of the Equator. Our plate of Europe was squeezed in between just as in a vice.