The Science Behind the Rocks of Vietnam's Halong Bay

[Indochina Sails]

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Situated in the Gulf of Tonkin, Ha Long Bay is one of todays New Seven Wonders of Nature. Ancient myth claims that a dragon was responsible for its formation but the facts lie within the rocks. The area offers stunning views of over 1,600 limestone karsts, or towering, eroded landmasses, and attracts tourists from around the world. Pillars can be seen in clusters or as individual islands. Due to the formation of the landscape, most of the islands are uninhabited. The vertical nature of each rock means they will likely remain untouched by humans

Vietnam is located near active tectonic plates. Over 500 million years ago the area was completely underwater. Over time the mountains were created by on and off periods of inverse motion. The tectonic activity laid the foundation for a shallow sea.

 

It was about 300 million years ago that finely-grained limestone rose above the water level. The land masses grew. Covered in lush greenery, a series of tropical jungles developed. Some limestone karsts are more than 1000 meters thick and home to a variety of birds, insects and animals, such as monkeys. Karsts are often a result of rain water containing carbonic acid. The compound begins to dissolve the surface along any cracks or bedding planes. As the bedrock break downs, the fractures enlarge. Openings continue to increase in size developing underground drainage systems. With these holes, more water can pass through and accelerate the formation of typical karsts features.

Marine erosion causes many islands and pinnacles to appear to be top-heavy or as if they are balancing on a smaller point. At the base of the formations, visitors can see residual lines of where the water has risen and decreased. As the sea level fluctuates, the wetting and drying of the limestone has its own effect on the geology of the bay.

 

Kayaking through the bay allows some exploration of small caves. Many of these passages will be lost if and when the sea levels rise again. There are, however, many large caves in some of the larger formations. Some are open for viewing with a tour or may even be part of your cruise itinerary when visiting Ha Long Bay.

Gazing at the majesty of Ha Long Bay is only the beginning of many tourists’ interaction. Kayaking, swimming and exploring the caves are all excellent ways to see the untouched haven that is exists within this natural wonder.