National Fossil Wood Park, Sathanur

National Fossil Wood Park at Sathanur, in Perambalur district, protects a bed of petrified wood in the Kaveri basin. M. S. Krishnan, a geologist with the Geological Survey of India, found the site in 1940, the year the park was set up, and in 1951 the Survey declared it a National Geological Monument. Part of the park is open to the public.

The fossils are conifer trunks from the Upper Cretaceous, roughly 100 million years old, and one of them stretches more than 18 m. They lie in the Kulakkalnattam Formation, marine sediments laid down on a coast shaped by strong winds and tides. In that period the sea rose over the land, and as it drew back, drowned trees and sea creatures were turned to stone. The plain around the park, worn down from Cretaceous rock and broken by isolated granulite hills, holds many shallow-marine fossils.