Miyajima
Itsukushima is an island in the western part of the Inland Sea of Japan, located in the northwest of Hiroshima Bay. It is popularly known as Miyajima, which in Japanese means "Shrine Island". The island is one of Hayashi Gahō's Three Views of Japan specified in 1643. Located in Hiroshima Bay, the influence of high and low tide has a geological peculiarity.
Wadden Sea
Wadden Sea, also known as tidal flats, are coastal wetlands that form when mud is deposited by tides or rivers. They are found in sheltered areas such as bays, bayous, lagoons, and estuaries. Mudflats may be viewed geologically as exposed layers of bay mud, resulting from deposition of estuarine silts, clays and marine animal detritus. Most of the sediment within a mudflat is within the intertidal zone, and thus the flat is submerged and exposed approximately twice daily. In the case of a Wadden Sea, the ground has only a slight slope, with the difference in altitude generally being less than one meter over a length of one kilometer. At the same time, the difference in water level between flood and low water is at least two meters, so that a sufficiently large area dries.
Mudflat
Mudflats or mud flats, also known as tidal flats, are coastal wetlands that form when mud is deposited by tides or rivers. They are found in sheltered areas such as bays, bayous, lagoons, and estuaries. Mudflats may be viewed geologically as exposed layers of bay mud, resulting from deposition of estuarine silts, clays and marine animal detritus. Most of the sediment within a mudflat is within the intertidal zone, and thus the flat is submerged and exposed approximately twice daily.
Sediment mudflat
Sediment mudlfat is formed by deposits of suspended matter, which were transported by rivers into the sea and settle in the intertidal zone. Depending on the predominant grain size of the sediments, different forms of mudflat arise. For all of them, the fine sand content with a particle size of 0.063-0.125 millimeters is 40-60%. The two "extreme forms" of the sediment mudflat, sand mudflat and silt mudlfat, are differentiated according to the proportion of silt and clay, the sediment fraction with a grain size of less than 0.063 mm. Not counting the actual mudlfats, the sandbanks where the proportion of coarser sand with 0.2 mm grain size is relatively high.
Generally, at low tide, sandworms have the firmer substrate, while silt mudlfat is usually relatively pliable. However, there are also places in sand mudflat, where the substrate is very soft and allows large sinking depths (quicksand), while silt mudflat can also be firm and resistant. The decisive factor in both cases is the saturation of the sediment with water. The higher the water content in the pore space of the sediment, the more unstable the substrate is.
Types of mudflat
1) Sand mudflat has less than 10% silt and clay. The content of organic matter and water is very low. The mudflat gets more energy through waves and wind and undergoes significant rearrangements. This makes it the oxygen richest mudflat.
2) Mixed mudflat has between 10% and 50% clay and silt content. The mixed mudflat is found in protected locations near the mainland, on watersheds, and partly also in the surf protection of the large islands.
3) Silt mudflat has claying and silting shares of over 50%. It is particularly protected places, e.g. in the interior of bays or in the lee of islands. It is less relocated than sand or mixed mudflats and is therefore particularly low in oxygen. This is mainly the location of the biodiversity, so that here are very nutrient-rich areas. The mudflat is particularly dark, because due to the oxygen depletion of the reduction horizon, in which hydrogen sulfide precipitates iron as iron sulfide and thus turns the ground black, is often only a few millimeters below the surface. Here are very extreme conditions. The fauna and flora of the sea must tolerate long dry seasons, high temperature fluctuations and low oxygen supply in the soil. Silty cotton takes by far the smallest part in the Wadden Sea. However, as it is often close to the coastline, tourists are more likely to notice it.