1, function
Continental island refers to an island similar or related to the mainland in geological structure. Generally located on the edge of the continent. The mainland island was originally a part of the mainland, but it was separated from the mainland due to the subsidence of the earth's crust or the rise of sea level. Such as Taiwan Province Island in China, Zhoushan Islands and British Isles in Europe.
2. the reason
There are also many reasons for the formation of mainland islands. Some of them were moraine mounds formed in the glacial environment of the ancient continent, and later became islands in the ocean because of the rising sea level. Some are islands formed by the separation of part of the original continent by seawater due to the strait formed by faulting or crustal subsidence. At the estuary, alluvial islands can be formed due to strong accumulation.
Second, volcanic island.
1, function
The volcanic island (Gaodao) is formed by the accumulation of volcanic eruptions (lava, volcanic ash, etc.). ). Widely distributed in the Pacific Rim, the area of volcanic islands is generally small, that is, there are single volcanic islands and archipelagic volcanic islands. Famous volcanic islands include Aleutian Islands and Hawaii Islands.
Volcanic islands can be divided into two types according to their attributes. One is an ocean volcanic island, which has nothing to do with continental geological structure. The other is a volcanic island in the continental shelf or slope, which is related to the continental geological structure, but not the same as the continental island, and belongs to the transitional type between the continental island and sea island.
2. the reason
Due to plate movement, lava flows overflow from the extinction boundary of collision between submarine plates, and the growth boundary between plates gradually increases, forming submarine volcanoes. The submarine volcano grows upward during the eruption process, which will expose the sea surface and form a volcanic island. At first, the submarine volcano was just a lava flow overflowing along the submarine rift, and then it gradually increased upwards.
Most of the magma erupted by submarine volcanoes is cooled by seawater and stops moving before reaching the sea. Therefore, people have never really seen the scene of submarine volcanic eruption. At most, I just saw the lava springs at the bottom of the sea spewing out new magma and forming new igneous rocks.
Three. reef island
1, function
Coral Island is surrounded by colorful scenery, which is one of the best places for water skiing, snorkeling, surfing and sailing in Phuket and the most popular tourist attraction in the south of Phuket.
2. the reason
Coral Island is named for its rich coral ecology. Surrounded by colorful coral reefs, it has beautiful scenery and is one of the best places for water skiing, snorkeling, surfing and sailing in Phuket.
Extended data:
Classification of mainland islands:
1, bedrock island
Most bedrock islands were originally part of the mainland. Later, due to the subsidence of the earth's crust or the rise of the sea surface, the sea flooded the lowlands, and the higher coastal mountains and hills were exposed on the sea surface to become islands, so they were similar to the adjacent land in geological structure and surface morphology. They are mainly distributed near the bedrock coast in mountainous areas.
90% of China's islands are located in the coastal areas of Zhejiang, Fujian and Guangdong, especially in Zhejiang, and most of China's islands are located in the East China Sea. Bedrock islands are mostly formed by the collapse of coastal mountains, and islands are mainly composed of mountains, often named after them. Such as Changshan Islands, Zhoushan Islands and Wanshan Islands.
2. Alluvial island
Sediments carried by many rivers entering the sea in China are alluvial islands in estuaries. It is also called accumulation island or sand island, because the sediment carried by the river is gradually accumulated at the estuary due to the slow flow rate and the action of tidal advance. There are many shoals in the Yangtze River estuary, among which Chongming Island is the largest, with an area of 1.083 square kilometers, making it the third largest island in China.
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