Judging from the surface morphology, Hainan Island is not connected to the main part of Eurasia, and is separated by the long Qiongzhou Strait from the Leizhou Peninsula in Guangdong Province. In fact, Hainan Island is part of the authentic Eurasian continent. Why are Hainan Island and Guangdong separated by seawater? Since the 1930s, scientists have studied the causes of the Qiongzhou Strait. After nearly a century, various explanations have gradually emerged.
Many geologists believe that Leizhou and Qiongzhou were originally integrated, but later under tectonic action, a rift was formed in today's Qiongzhou Strait, thus separating Hainan Island from the mainland (Leizhou Peninsula). The plate in the Leiqiong area was rifted during the Paleogene, forming the original Qiongzhou Strait-a shallow sea including the entire Leizhou Peninsula; subsequently, volcanic eruptions occurred in Leinan and northern Qiongbei, rising to form land, and the shallow sea between them became deeper and twice the width of the modern strait; then, the area experienced many rifting and uplifting movements, and the Qiongzhou Strait began to narrow; in the late Pleistocene and Holocene of the Quaternary, active geological activities slowly subsided; At the peak of the last ice age, the global sea level dropped significantly, and the Qiongzhou Strait in the tropical area was also affected and turned into a river erosion valley; in the post-glacial period, as the sea level rose, it became the modern Qiongzhou Strait.
However, some people have also suggested that the formation of the Qiongzhou Strait was mainly due to sea erosion. In the coastal zone between the Leizhou Peninsula and Hainan Island, the surface material is loose and washed by waves and currents from both the Beibu Gulf and the South China Sea. It is very easy to collapse and collapse into the sea. After a long geological era, the sea water gradually penetrated and rushed out of the Qiongzhou Strait.
Others believe that the formation of the Qiongzhou Strait was related to post-glacial transgression events. In the middle of the Holocene, the surface material in the area where the Qiongzhou Strait is located was soft, making it easy to collapse or slide, and gradually turned into lowlands and valleys. Although it was in the middle of the Holocene ice age and the climate did not have much impact on the Qiongzhou Strait, the subsequent ice age shifted to the interglacial age, and the sea level rose globally. Seawater may soak through lower surface areas, dividing the land into isolated islands. The Qiongzhou Strait was formed.