Welcome to our Nature Guide
Limestone karst gives Phang Nga its complicated beauty. And anything this beautiful is always complicated. The first important geology happened 300 million years ago when South East Asia was the largest coral reef in history. Obviously formed under the sea, the crescent-shaped reef ran from Bali and Borneo north off
When all the large islands were connected into one land mass it was a subcontinent called the "Sunda Shelf''. Look closely at the
channels between the islands, and you can see that many ridge lines were actually connected before the elements eroded them apart.
Tidal currents running down the Bay hit North Panak head-on. Their power ate away two galleries of sea level, creating a nape that is both high and wide. The 1 top level was created first, allowing the exterior stalactites to form. It all makes for a great paddle in the shade.
With its origins in coral, limestone is brittle.You see countless cracks or faults in the rock created by pressure.When large faults slip, the limestone breaks off in blocks, often big enough to become these islands.Imagine huge limestone blocks floating on the Earth's crust
like a cube of ice
floating in a glass of water. When continental plates drift, the limestone spins and bobs up and down just like ice does when you put your finger on the cubes. These cracks collect oxide before the rock rotates again, taking the iron ore high above sea level. Percolation enlarges the cracks, depositing particulates "downstream" as flowstone. Caves form along these cracks when water percolates downhill, filling the cavern with stalactites. Some cave roofs have holes leading to either sunlight or another cave, the earliest point of Hong creation. Eventually, the cavern will collapse, one way of forming a "Hong", which is Thai for chamber or room.
The top photo shows exterior stalactites created by percolation, and a long, deep Hong created by a collapsed semi-tidal cavern. The cavern remains at the back of the 2K "overnighter" Hong, relentlessly percolating away.
The bottom cave sits in mountains at the top of the Peninsula. It's easy to see how this river cave runs along a fault line, and how water seeping down the fault formed these stalactites.
Water is today's theme. You are obviously surrounded by sea water, but it's rain water that creates the bizarre karst that attracts people to Phang Nga Bay. Even in thedry season, rainwater drips down inside the cave in a never-ending process that eatsaway the islands.Heavy rainfall creates karst, so these grotesque shapes are usually found in the Tropics. The combination of raised reef limestone in a tropical monsoon region creates this great karst region.
The process that dissolves particles in the water that flows down through the island is called "Percolation" - in the same way as percolating water goes through coffee grounds. Clear water picks up the coffee molecules as it runs through the grounds, and drips brown-colored coffee into the pot.