A waterfall that builds itself taller by 5mm every year. Dissolved limestone crystallizing on every surface; growing terraces like frozen waterfalls.
Khunkay, CC BY-SA 3.0, via Wikimedia Commons
The self-constructing cascade
Khlong Lan is a waterfall that actively builds itself. The process begins as rainwater, made slightly acidic by atmospheric carbon dioxide, seeps through the soil and into the rock of the Dawna Mountain Range. The water dissolves calcium carbonate (CaCO3) from the underlying limestone and granite, carrying it in solution. When this mineral-rich water emerges and cascades down the 100-meter-high cliff face, it undergoes a rapid chemical change.
The turbulence of the fall vigorously aerates the water, causing it to release its dissolved carbon dioxide. This CO2 loss makes the water less acidic, reducing its capacity to hold dissolved calcium carbonate. The mineral then precipitates out of the solution, crystallizing as a form of limestone called travertine. This process is most effective in warm, humid climates, making the subtropical environment of Khlong Lan an ideal location for travertine formation.
A living stone formation
The constant precipitation of calcite builds upon every surface the water touches. Over immense timescales, this accumulation creates the waterfall's distinctive, flowing rock formations and terraced pools, known as gours. The rate of deposition is slow, estimated at up to 5 millimeters per year, but relentless. This incremental growth means the waterfall is not eroding the cliff but actively constructing it, layer by layer.
The water of Khlong Lan pours over a cliff approximately 100 meters high and 40 meters wide. This cascade originates from the convergence of five smaller creeks in the Khun Khlong Lan mountains, which reach a peak elevation of 1,439 meters. The resulting flow is powerful enough to sustain this geological process year-round, ensuring the slow, steady growth of the travertine deposits. Algae and moss that colonize the wet surfaces can act as a substrate for calcite nucleation, trapping the mineral particles and accelerating the build-up of the rock.
💡Fun Facts
The process of travertine formation at a waterfall is chemically similar to the way stalactites and stalagmites form inside caves.
The large plunge pool at the base of the main 100-meter drop is deep enough for swimming in designated areas.
Khlong Lan National Park was established on December 25, 1982, as the 44th national park in Thailand.
The rock face behind the waterfall is primarily granite, with the water sourcing its minerals from limestone higher in the catchment area.
