Krabi — Karst Landscape

Trip: 22–12–2019 to 05–01–2020

As an inquisitive climber, I naturally wonder how those beautiful limestone cliffs in Krabi were crafted. I can’t help but to look up the geology of Krabi.

Tectonics

425M years ago (Ma), Thailand is a coral reef, a submerged island in a shallow sea.

90Ma, sea level is 200–300 meters higher than today, and the ‘Tower Karst’ of Krabi likely begin to take shape.

60Ma, the Indian subcontinent collided with mainland Asia. The limestone along Thailand was thrust up above sea level.

Left: India collided with mainland Asia. Major trenches and ridges in East Asia (Earth Observatory of Singapore, 2019); Middle: The India plate is colliding with mainland Asia over tens of million years (Van der Voo et al., 1999); Right: The Indo-Australian plate is colliding into the Eurasian plate at a speed of 70mm/year (Chula International Communication Center, 2017).

Chemical and Weather process

Rain water + atmospheric CO2 →mildly acidic water (carbonic acid H2CO3)
Water seeps through soil → picking up more CO2 (released by roots of plants can be x15 of atmosphere!)

Warm humid climate favours vegetation, e.g. mangrove forests, thus, acidic soil water dissolves limestone aggressively. As water seeps through cracks and dissolve limestone, underground drainage systems develop.

When the roof of a huge cave chamber collapses, a ‘Hong’ (Thai for “room”) is created. One of the top must-visit in Krabi, Koh Hong, is named after the room-like lagoon at the center of the island.

The Karst landscape is shaped by a geological process over many thousands of years: the dissolving action of water on limsetone (layers of sea shells formed millions of years ago) which results in caverns, pinnacles, towers, sinkholes, underground streams.

Krabi is worth going for the spectacular view, the amazing food, the beautiful beaches, a dip is a must during a hot sunny day, and of course lots of fun climbing routes — the rock climber’s paradise (if you don’t mind the heat)!

Left: Morning in Railay West (23–12–2019); Middle: Hong Lagoon (01–01–2020); Right: Koh Pakbia (01–01–2020)