Ha Long Bay - Cat Ba Archipelago has just been recognized by the International Union of Geological Sciences (IUGS) as one of the 100 international geological heritage sites.
This title was announced at the 37th International Geological Congress, scheduled to take place in Busan, South Korea, from August 25-31, 2024.
The IUGS evaluated that Ha Long Bay - Cat Ba Archipelago made it to the list of 100 international geological heritage sites after a thorough, scientific selection and assessment process by 85 of the world's leading experts.
According to the IUGS assessment, Ha Long Bay - Cat Ba Archipelago is included in the list of exceptional sites in terms of geomorphology, geology, and surface geological processes. The Ha Long Bay - Cat Ba Archipelago complex is a unique and exemplary global illustration of limestone mountains formed in the sea due to geological transformations and sea water erosion.
The geological history of Ha Long Bay - Cat Ba Archipelago's limestone has spanned approximately 500 million years with varying paleo-geographic conditions, and the complete karst evolution process has occurred over more than 20 million years. This evolution involved factors such as thick limestone layers, a hot and humid climate, and a slow tectonic uplift process overall.
In terms of geomorphology and geology, Ha Long Bay - Cat Ba Archipelago is clearly one of the most comprehensive and widely recognized global examples of submerged karst towers. It is also one of the most important areas for Fengcong (cone karst peaks) and Fenglin (isolated tower features) karst.
The marks of geological evolution and tectonic movements left behind include faults, folds, grabens, horsts, and basins that signify profound changes in the region's paleo-geographic conditions.
Moreover, the sea directly participates in the karst process here, creating distinctive features such as marine notches and marine notch caves, and marine tunnels. The sea also submerges sinkholes, dolines, and karst valleys, forming saltwater lakes, or "tungs" and "angs." The caves in this area are abundant and diverse, belonging to three main groups: ancient underground caves (hanging caves), karst base caves, and marine notch caves.