Khao Sok’s relevant geologic history begins approximately 345 million years ago, during the Carboniferous period. At this time, the Shan Thai craton (a craton is an extremely old chunk of land that has been relatively stable) was actively eroding. Ancient mountains of the craton’s interior were slowly transferring their mass, via rivers carrying off gravels, sands, silts and mud, onto the continental shelf of the craton. This was similar to the modern day process of major river deltas (like the Mississippi or the Nile) extending out into the sea from the land. The sediments would accumulate on the edge of the shelf, just above a deep ocean basin. Every so often, the sediment pile would catastrophically collapse into the basin, sometimes triggered by earthquakes, to form chaotic deposits known as turbidites.