1. Continental Islands
1. Characteristics
Continental islands refer to islands that are similar or connected to the mainland in terms of geological structure. Generally located on the edge of continents. The mainland island was originally part of the mainland, but was later separated from the mainland due to crustal subsidence or rising sea levels to form an island. Such as Taiwan Island, Zhoushan Islands in China and the British Isles in Europe.
2. Causes
There are also many reasons for the formation of mainland islands. Some mainland islands are moraine hills formed in the ancient continental glacier environment, and later became the glaciers in the ocean due to rising sea levels. islands. Some are islands formed by straits formed by faults or subsidence of the earth's crust, which separated part of the original continent from the sea. In large river estuaries, alluvial islands can be formed due to strong accumulation.
2. Volcanic Island
1. Characteristics
Volcanic Island (High Island) is formed by the accumulation of volcanic eruptions (lava, volcanic ash, etc.) . They are widely distributed in the Pacific Rim. The area of ??volcanic islands is generally not large. There are single volcanic islands and archipelago-style volcanic islands. Famous volcanic island groups include the Aleutian Islands, Hawaiian Islands, etc.
Volcanic islands are divided into two types according to their attributes. One is an oceanic volcanic island, which has no connection with the continental geological structure; the other is a volcanic island on the continental shelf or continental slope sea, which is connected with the continental geological structure. It is related but different from the mainland island. It is a transitional type between mainland islands and oceanic islands.
2. Causes
Due to plate movement, the lava flow overflowing from the death boundary of the collision of various plates on the seafloor and the growth boundary between the plates gradually increased upward, forming submarine volcanoes. Undersea volcanoes continue to grow upward during eruptions and will emerge from the sea to form volcanic islands. Undersea volcanoes begin as lava flows that overflow along ocean floor rifts, and then gradually increase in height.
The magma erupted by most submarine volcanoes is cooled by the sea water before reaching the sea surface and is no longer active. Therefore, people have never really seen the scene of submarine volcano erupting. At most, you just see the lava springs on the sea floor constantly emitting new magma to form new igneous rocks.
3. Coral Island
1. Characteristics
Coral Island is surrounded by various colorful and beautiful scenery. It is the most suitable place for skating in Phuket. One of the best places for water activities such as snorkeling, surfing and sailing, it is the most popular tourist attraction in southern Phuket.
2. Causes
Coral Island is named after its rich coral ecology. The island is surrounded by various colorful coral reefs and has beautiful scenery. It is the most beautiful coral island in Phuket. One of the best spots for water activities such as water skiing, snorkeling, surfing and sailing.
Extended information:
Classification of mainland islands:
1. Bedrock Islands
Most of the bedrock islands were originally part of the mainland Later, due to crustal subsidence or sea level rise, the seawater flooded the lowlands, and the higher coastal mountains and hills were exposed on the sea surface and became islands. Therefore, they are similar to adjacent land in terms of geological structure and surface morphology. They are mainly found near mountainous bedrock coasts.
90% of the country’s islands are distributed along the coasts of Zhejiang, Fujian and Guangdong, especially in Zhejiang. Most of my country’s islands are distributed in the East China Sea. Bedrock islands are mostly formed by the collapse of coastal mountains. The islands are mainly composed of mountains and are often named after mountains. Such as Changshan Islands, Zhoushan Islands, Wanshan Islands, etc.
2. Alluvial Islands
The sediment carried by many rivers entering the sea in my country is alluvial at the river mouth to form alluvial islands. It is formed by the gradual accumulation of sediment carried by rivers at the mouth of the river due to the slowdown of the flow rate and the support of the tide, so it is also called an accumulation island or a sand island. There are many sandbars and shoals in the estuary section of the Yangtze River. The largest sandbar is Chongming Island, covering an area of ??1.083 square kilometers. It is the third largest island in my country.
Baidu Encyclopedia - Mainland Island
Baidu Encyclopedia - Volcanic Island
Baidu Encyclopedia - Coral Island