The formation of multiple shell banks

Question 1: Explanation of shell dike This entry is a disambiguation entry. Shell dike is composed of marine shells and their fragments and thin layers of fine sand, silt sand, peat, and silty clay. A dike-like landform accumulation that is roughly parallel to the coast or has a small intersection angle. Formed near the *** line, it is a reliable landmark of the ancient coast. There are three famous shell embankments in the world, namely the shell embankment in Tianjin, China, the shell embankment in Louisiana, the United States, and the shell embankment in Suriname, South America. Shell banks have been an important object of research by scientists for decades and occupy an important position in the international research fields of oceans, Quaternary geology, paleoclimate, and paleoenvironment. This entry introduces Tianjin Shell Dike. Shell Dike is commonly known as "Clam Dike", "Sha Lingzi" and "Lingzi Barrier". The ancients called it "shell mound"; geomorphologists call it "the coastal embankment of death". Shell embankment is a unique landform in Tianjin. It is a symbol of the ancient Bohai coastline that was gradually accumulated by marine shellfish driven by the tide over thousands of years. The shell embankment truly records the process of Tianjin's changes in the sea and the land. The shell embankment in Baishaling, Junliang Town, Dongli District, is the historical footprint of the changes in sea and land. Shell banks are accumulations formed in silty silt coastal areas where washed biological shells are washed toward the shore under the action of waves. The scouring of waves increases the slope of the beach and coarsens the bottom. The shellfish at the bottom are washed to the shore by the sea water and accumulate near the bottom line. After a long period of time, a shell bank is formed. When the source of sediment in the coastal zone is sufficient and the sediment accumulation on the beach is strong, shell banks stop developing. Multiple erosion and siltation changes have left many shell banks. It can be used as a symbol of ancient coastline migration. Using C14 isotope dating to determine the age of shell formation, the history of coastal development can be restored. The formation of shell banks requires three conditions, namely silt banks, relative seawater erosion background and abundant shell sources. Historically, the Yellow River is known for its "good siltation, good determination, and good migration." The Yellow River carries a large amount of fine-grained loess material, which migrates repeatedly on the south and west banks of the Bohai Bay over a long period of time, creating the largest silt coast in the world. When the Yellow River changed its course and its mouth moved elsewhere, as the amount of sediment entering the sea decreased, siltation on the coast stopped growing, the sea water became clear, and a wide variety of marine molluscs continued to thrive, providing a sufficient source of shells. The most important thing is the tidal movement of the sea, mainly erosion, which moves the shells to the coast and accumulates them. As the shells accumulate year by year, a unique shell ridge coast is formed. Once the Yellow River changes course and moves back, the shell embankments and silt banks with relatively fresh and turbid sea water are not conducive to the growth of shells and will stop. Outside the shell embankment, sediment accumulates into land, and the coastline extends forward. The shell embankment is far away from the coast, either abandoned on land or buried underground. Therefore, due to the back and forth migration of the Yellow River, the coastline stops and goes, and the silt and shell embankments alternate. Multiple shell embankments parallel to the coastline are formed on the south and west shores of the Bohai Bay, which also become the footprints of the Bohai Bay coastline extending to the Bohai Sea. Tianjin Shell Dike is located in Jinnan, Dagang, Tanggu and other places in eastern Tianjin. It is part of the "Tianjin Ancient Coast and Wetland National Nature Reserve". The entire reserve consists of Shell Dike, Oyster Beach and Qilihai Wetland Ecosystem. It is an ancient Extremely precious marine relics of coastal changes. Research on shell banks, oyster beaches and wetlands has been carried out in Tianjin for decades. It has become an important place for marine, geological, geographical and other systems and institutions to study coastal evolution, paleoclimate, wetland ecology and other disciplines. In the Tianjin land accumulation plain, there are four shell banks I, II, III and IV arranged from land to sea. They are roughly parallel to the modern coastline and distributed in a ridge-shaped discontinuity, representing the position of the coast in the four periods. Most of the Tianjin Plain was flooded due to sea intrusion that occurred between 10,000 and 5,000 years ago. Later, the sea level dropped, the rivers alluvialized, and gradually formed land. The shell embankment is a relic left by this historical process. It is a distinctive coastal landform type in the Tianjin coastal zone. It is also a relic of the ancient coast of Bohai Bay, reflecting the changes in the coastline from land to sea. There are many kinds of shells on the embankment, most of which are living species of intertidal zone or shallow sea mud and bottom molluscs. There are many types of shells on the embankment. These ancient oyster shells are about 30 centimeters long. They are very rare and rare and can no longer be found today. Tianjin shell embankments are 0.5 to 5 meters high, tens to hundreds of meters wide, tens of meters long, hundreds of meters long, or extend for more than a hundred kilometers. The top of its cross section is convex, and its wings are thinned to the point of extinction. The shell banks and oyster reefs in the Tianjin Ancient Coast and Wetland Nature Reserve have the characteristics of large scale, good exposure, strong continuity, and clear sequence. They are the most typical on the eastern coast of China and rare even on the western Pacific coast. The establishment of a protected area can protect these non-renewable geological landscapes, and at the same time provide extremely valuable natural data for the study of sea and land changes, paleogeography, and paleoclimate in Tianjin and the eastern coast of China... >>

< p> Question 2: The formation of Tianjin shell embankment. It turns out that old Tianjin people called ancient shell embankment clam embankment. It was formed by the deposition of ancient shells and can reflect the changes of coastal sea and land. Tianjin’s ancient shell embankment is one of the three largest in the world. One of the ancient shell dikes, it is of great significance for understanding the geological evolution of Tianjin. As a special type of coastal embankment, ancient shell embankments must be formed with conditions such as substrate, slope, and hydrodynamics that are suitable for shellfish to reproduce and be brought to the shore for accumulation by strong winds and waves. Therefore, the location of the ancient coast can be determined based on the location of the ancient shell dikes, and the evolution and dynamics of the coast can also be analyzed based on the relationship between the old and new shell dikes.

Shell embankments are embankment-like landform accumulations composed of marine shells and their fragments and thin layers of fine sand, silt sand, peat, and silty clay. They are roughly parallel to the coast or have a small intersection angle. It was formed near the first line of the sea and is a reliable landmark of the ancient coast. The Holocene transgression that occurred between 5,000 and 10,000 years ago flooded most of the Tianjin Plain. Later, the sea level dropped, the rivers alluvialized, and gradually formed land. The shell embankment is a relic left by this historical process. It is a unique coastal landform type in the Tianjin coastal zone, reflecting the changes in the coastline from land to sea. The embankment is 0.5 to 5 meters high, tens to hundreds of meters wide, tens of meters long, hundreds of meters long or extends for more than 100 kilometers. There are many kinds of shells on the embankment, most of which are living species of intertidal zone or shallow sea mud and bottom molluscs. Shellfish like to grow and reproduce on the clear, translucent, nutrient-rich fine sand and silty sandy bottom of the sea. Under the action of waves, especially strong waves, and under the conditions of suitable bank slopes, shells and sand accumulate, and finally * Shell banks are generated near the line. The Yellow River is a world-famous river with a large sediment content. It has changed its course seven times. When it swings to Shandong and enters the sea, the natural conditions along the coast of Tianjin are conducive to the formation and development of shell embankments. When it moves north to Tianjin and enters the sea, the turbidity of the seawater increases. , the bank slope slope becomes gentle, and its ecological environment and dynamic conditions are not conducive to the formation of shell embankments. Therefore, the shell bank not only represents the location of the coastline at a certain period, but also reflects the geographical environment at that time. Since the 1970s, the C isotope absolute dating method and archaeological methods have been used to study the formation period of the shell embankment. It is generally believed that the formation of the III embankment was about 3500 years ago in the Yin Shang Dynasty; the II embankment was formed about 2000 years ago. It was formed during the Warring States Period; the first embankment appeared at the end of the Yuan Dynasty and the beginning of the Ming Dynasty. From this we can understand the development process of coastal land formation in Tianjin area.

Question 3: Explain the relationship between the formation of shell embankments and the coastal erosion and siltation environment. Shell embankments are commonly known as "clam embankments", "shalingzi" and "lingzi barriers". The ancients called it "shell mound"; geomorphologists call it "the coastal embankment of death". Shell banks are symbols of ancient coastlines formed by the gradual accumulation of marine shellfish driven by ocean tides over thousands of years. The shell embankment truly records the process of changes in the coastal area and is the historical footprint of changes in the sea and land.

Shell banks are accumulations formed in silty silt coastal zones where washed biological shells are washed toward the shore under the action of waves. The scouring of waves increases the slope of the beach and coarsens the bottom. The shellfish at the bottom are washed to the shore by the sea water and accumulate near the bottom line. After a long period of time, a shell bank is formed. When the source of sediment in the coastal zone is sufficient and the sediment accumulation on the beach is strong, shell banks stop developing. Multiple erosion and siltation changes have left many shell banks. It can be used as a symbol of ancient coastline migration. Using C14 isotope dating to determine the age of shell formation, the history of coastal development can be restored.

The formation of shell banks requires three conditions, namely silt banks, relative seawater erosion background and abundant shell sources.

Question 4: Where is Shell Dike? Shell Dike is located in Jinnan, Dagang, Tanggu and other places in eastern Tianjin. The shell dike is an ancient marine relic dating back more than 7,000 years. It is a dike-like landform composed of marine shells and their fragments, and thin layers of fine sand, silt sand, peat, and silty clay under the action of tides, wind and waves. accumulation body.

Question 5: Introduction to shell embankments Shell embankments are composed of marine shells and their fragments and thin layers of fine sand, silt sand, peat and silty clay. They are roughly parallel to the coast or at a small angle. Dike-like landform accumulation body. Formed near the *** line, it is a reliable landmark of the ancient coast. Shell banks have been an important object of research by scientists for decades and occupy an important position in the international research fields of oceans, Quaternary geology, paleoclimate, and paleoenvironment. This entry introduces Tianjin Shell Embankment.

Question 6: What is the reason for the formation of shell embankments? What is the climate, weather, and accumulation over time?

Question 7: Introduction to Tianjin Shell Embankments. Tianjin Shell Embankments are one of the three world-famous ancient shell embankments. One (the other two are the Shell Dock in Louisiana, USA, and the Shell Dike in Suriname, South America) has been an important object of research by scientists for decades and occupies an important position in the international ocean, Quaternary geology, paleoclimate, and paleoenvironment research fields. . It is part of the "Tianjin Ancient Coast and Wetland National Nature Reserve". The entire reserve consists of shell embankments, oyster beaches and the Qilihai Wetland ecosystem. It is an extremely precious marine relic of ancient coastal changes. Research on shell banks, oyster beaches and wetlands has been carried out in Tianjin for decades. It has become an important place for marine, geological, geographical and other systems and institutions to study coastal evolution, paleoclimate, wetland ecology and other disciplines.

Question 8: How to get to Binzhou Shell Embankment? On January 25, 2002, the People's Government of Shandong Province approved the establishment of the Wudi Shell Ridge Island and Wetland System Provincial Nature Reserve. The protected area covers an area of ??80,480 hectares. The main protection objects are the shell ridge beach marine natural heritage and wetland biological systems. . On February 17, 2004, it was renamed Binzhou Shell Island and Wetland System Provincial Nature Reserve.

Wudi Shell Embankment Island and Wetland System Provincial Nature Reserve is located in the north of Wudi County, Shandong Province, on the southwest coast of the Bohai Sea, extending to Zhangweixin River in the west, Taoer River in the east, and Qianhai-3 in the north. meter isobath line, south to Zhangshanzi-Lishanzi-Xiabotou-Yangzhuangzi line.

The geographical coordinates are: 37°54′30″～38°19′10″N, 117°45′08″～118°05′37″E. There are two rows of ancient shell embankments in the northern part of the territory. The first row is north of Chengkou Town, located on the line Zhangjiashanzi-Lijiashanzi-Xiabotou-Yangzhuangzi. It is nearly 40km long, buried deep 0.5-1 meter, and the shell layer is thick. 3-5 meters, formed in the middle of the Holocene, about 5000 years ago; the second row is in the northeast of Chengkou Town, located on the line of Dakou River-Wangzibao-Zhaoshazi, nearly 22Km long, and composed of more than 40 shell islands. The island is 100-500 meters wide and the shell layer is 3-5 meters thick. It is an extremely open type and was formed in the late Holocene, 2000-1500 years ago. The two embankments are connected to the shell embankment in Hebei Province, forming a large-scale shell beach ridge coast that is rare in the world and unique in China, and is known internationally as the Chenier Coast.

Shell embankment island is a unique geological landform formed under specific geological conditions and geographical environment. Compared with shell embankments of the same type at home and abroad, Wudi Shell Embankment Island has several unique features. First, the shell content is high. Whether it is buried deep underground or on the surface of Wudi Ancient Shell Bank Island, the shell content reaches almost 100%, with very few other impurities. Second, the old and new shell banks coexist, and there is no Di Beike Island not only has ancient shell berms dating back 5000-2000 years ago, but also has newly developed new shell berms, and has the tendency to form a third shell berm island. Other foreign and domestic shell berms are far away from the coast. , there is no possibility of forming new shell embankments; third, it is a typical shell tidal flat wetland ecosystem, which is a precious marine heritage of our province, our country and even the world, and has important scientific research significance and practical production value.

Wudi Shell Dike Island and Wetland System Provincial Nature Reserve is the most complete shell embankment in the world and the only one where old and new shell embankments coexist to protect the shell embankment island and wetland ecosystem and rare and endangered birds. as the main protected area. It is a transit station for migratory birds from inland Northeast Asia and the Western Pacific, and a paradise for birds to overwinter, inhabit, and breed. It is an important base for studying environmental evolution such as changes in the Yellow River, coastline changes, and the formation of shell embankment islands, as well as wetland types. It occupies an extremely important position in the research of marine geology, biodiversity and wetland types in my country.

Question 9: Are there still shells in Shell Dike? The so-called Shell Dike in Tianjin should be the Shell Dike Wetland Park. Right at the Ecological Park, you can go all the way north along TEDA's Central Avenue. Pass by there. But to be honest, that's what I personally feel. There are too many artificial factors and the so-called natural feeling is lost. Or maybe we grew up in Tanggu and are used to seeing truly wild shell beaches, but there are none now. Because all the land reclamation was buried.

Question 10: Where is Wudi Shell Island? Go to Wudi County and go north to Chengkou. There is a road north of the gate of Lubei Chemical Industry. Follow the road east by north. The sign says "Dakou River" on the road and just follow the road to the end. +1

The place upstairs is right, I have been there too, but is it that good? This is a matter of opinion. I wore a pair of singlets when I went there in August. It was very windy and quite cold at the beach. It must be very cold now. There are some sellers of seafood on the road, all of which are freshly caught, cheap and fresh. The shell embankment is very long, and it is said that it will grow by itself, but because there are so many people there, the shells are basically trampled to pieces, and they are not the big ones, they are all small shells. There are many small bird eggs on the beach. I don’t know what kind of bird they are. They are just in twos and threes on the shell beach. The sea in Wudi is actually not beautiful, but there is something special about going there to enjoy the breeze.